Full text of "An introduction to entomology, or, Elements of the natural history of insects : with plates [electronic resource]"

See other formats

KING'S
College

LONDON

Library

e >vT/Z*f^«/cr <e<?v\/ To

200999859 0

KING'S COLLEGE LONDON

■I

(

!
I

(

!
I

Digitized by the Internet Archive
in 2015

https://archive.org/details/b21299900_0003

INTRODUCTION

ENTOMOLOGY:

ELEMENTS

OF THK

NATURAL HISTORY OF INSECTS:

WITH PLATES.

By WILLIAM KIRBY, M.A. F.R. and L.S.

RECTOR OF BARHAM,
AND

WILLIAM SPENCE, Esq. F.L.S.

VOL. in.

LONDON:

FRINTEO FOK

LONGMAN, HEES, ORME, BROWN, AND GREEN,
PATERNOSTER ROW.

1S26.

PUINTED BY HICMAllD TAYLOU,
SHOE LANE, LONnON.

ADVERTISEMENT.

IHE publication of the concluding- volumes of
the " Introduction to Entomology" has been un-
avoidably delayed by the continued ill health of
one of the Authors, which has devolved upon the
other a considerable increase of labour, and de-
manded a greater expenditure of time than would
otherwise have been required : for though Mr.
Spence put every facility in Mr. Kirby's power,
and had drawn up a rough copy of every Letter
belonging to his department; yet, as most of
them had been written several years ago, many
curious facts, and a great variety of interesting
information subsequently derived from various
sources, were necessarily to be inserted, and the
whole to be prepared for the press.

When the thousands of objects that were to be
examined, and many of them repeatedly, in com-
posing the Letters on the External Anatomy of
Insects, are considered, it will not appear sur-

iv ADVERTISEMENT.

prising if some errors should have crept in; espe-
cially as Mr. KiRBY was deprived of the effectual
help formerly derived from the acumen, learning,
and judgement of his esteemed coadjutor, by his
lamented and protracted indisposition ; but it is
hoped that these errors will be found of minor
importance, and not to affect any general prin-
ciples advanced. The same remarks are also in
part applicable to the Anatomical and Orismolo-
gical Tables (Vol. III. p. 354—393, and Vol. IV.
p. 257—354), which were drawn up by the Au-
thors jointly ^ many years ago, before any other
portion of the work was composed, but which
have, especially the former, required considerable
alterations and additions in consequence of sub-
sequent observations and information.

It will not be amiss here to state, in order to
obviate any charge of inconsistency in the pos-
sible event of Mr.KiRBv's adverting in any other
work to this subject, that though on every material
point the authors have agreed in opinion, their
views of the theori/ of instinct do not precisely
accord. That given in the second and fourth
volumes is from the pen of Mr. Spence.

It was originally intended, as mentioned in the
Preface, to have given a complete list of Entomo-

ADVERTISEMENT.

logical works, of which a large portion was drawn
up; but the great length to which more important
matters have extended, has rendered necessary
the intire omission of this list, — an omission in
some degree compensated by the catalogue of
Authors quoted, which comprises most of the
standard Entomological works.

ERRATA.

Page. Line.

29 27, for Pseudo-cordia read Pseudo-cardla.
33 1 , for read \\.

35 7 and elsewhere, for Gigas read grandis.

46 16, for number and situation read in some respects.

98 6, for Furtina read Jurtina.

121 note ^, for c read cf.

135 note ^/or XXIV. read XXIII.

137 note "./or 17 read 18.

251 4, ybr ten read nine.

378 10 )

' i for froenum read frajnum.
359 21, i

422 note \ for a' read a".

425 note for h" read b'.

471 1, dele Pelecotoma.

10, for orbicular read subtriangular.

512 antepenult. Jfter genera insert^ except in some Aaidee,&& A.viri-

dissima.

562 note °, for 'prnu read wvu/ai.

606 5, for Heteropterous read Homopterous.

DIRECTIONS TO THE BINDER.

The Synoptical Table of the Nomenclature of the Parts of the
External Crust of Insects should be placed opposite to page 354.

Plates VI— XX. should be placed in this Volume, and the re-
mainder in the Fourth.

It is however suggested to Piurchasers, that in binding complete
Sets of the Work, a separate Volume may be formed of the Synop-
tical Table, the Plates and their Explanations, and the Indexes.

CONTENTS OF VOL. III.

Letter, Page..
XXVIII. Definition of the Term Insect 1—51

XX.IX. States of Insects. Egg state 52— 104<

XXX. The same Subject continued. Larva

state 105—237

XXXI. The same Subject continued. Pupa

state 238—290

XXXII. The same Subject continued. Imago

state 291—347

XXXIII. External Anatomy of Insects. Terms

and their Definition 34<8 — 393

XXXIV. The same Subject continued. The Head

and its Parts 394. — 528

XXXV. The same Subject continued. The

Trunk and its Parts and Organs . . 529 — 697

XXXVI. The same Subject continued. The Ab-

domen and its Parts 698 720

NOTICE RESPECTING VOL. I. and II.

It being judged expedient, since the publication of the last Edition of
the first and second Volumes of this Work, to adopt a new plan with
respect to the reference letters of the Plates, the Reader is requested to
make the following corrections in those Volumes.

Vol. I.

Page. Note.
125 for f, d read a".

273 for a read a.

395 % /yr 29, 30 read 13.

Vol. II.

244 for a read a.

319 ^ for 10 read 14.
348 for a read e'".

353 ^, for 7—. read 16 — .
366 for a read s", v".

for b read t".

405 ^, for 1.8. aa read 18. cf.
^, for bb read q".

406 *, for bb read C".

407 S for cc rcorf C"C", which represent the bundles of mus-

cles in connexion with the drums. In tlie above figure
the mirror is the part directly under those bundles.

INTRODUCTION

ENTOMOLOGY.

LETTER XXVm.

DEFINITION OF THE TERM INSECT.

What is an insect? This may seem a strange ques-
tion after such copious detiiils as have been given in my
former Letters of their history and economy, in whicli it
appears to have been taken for granted that you can an-
swer this question. Yet in the scientific road which yoa
are now about to enter, to be able to define these crea-
tures technically is an important first step which calls for
attention. You know already that a butterfly is an insect
—that a fly, a beetle, a grasshopper, a bug, a bee, a
louse, and flea, are insects— that a spider also and centi-
pede go under that name; and this knowledge, which
every child likewise possesses, was sufficient for compre-
hendmg the subjects upon which I have hitherto written.
But now that we are about to take a nearer view of them—
to investigate their anatomical and physiological charac-

VOT., III. J,

DEFINITION OF THE TERM INSECT.

ters more closely — these vague and popular ideas are
insufficient. In common language, not only the tribes
above mentioned, but most small animals — as worms,
slugs, leeches, and many similar creatures, are known by
the name of msects. Such latitude, however, cannot be
admitted in a scientific view of the subject, in which the
class of insects is distinguished from these animals just as
strictly as beasts from birds, and birds from reptiles and
amphibia, and these again from fishes. Not, indeed,
that the just limits of the class have always been clearly
understood and marked out. Even when our corre-
spondence first commenced, animals were regarded as
belonging to it, which since their internal organization
has been more fully explained, are properly separated
from it. But it is now agreed on all hands, that an
earthworm, a leech, or a slug, is not an insect ; and a
Naturalist seems almost as much inclined to smile at
those who confound them, as Captain Cook at the island-
ers who confessed their entire ignorance of the nature of
cows and horses, but gave him to imderstand that they
knew his sheep and goats to be birds.

You will better comprehend the subsequent definition
of the term Lisect, after attendmg to a slight sketch of
the chief classifications of the animal kingdom, more es-
pecially of the creatures in question, that have been pro-
posed. That of Aristotle stands first. He divides ani-
mals into two grand sections, corresponding with the Ver-
tehrata and Invertehrata of modern Zoologists : those,
namely, that have blood, and those that have it not^* :—
by this it appears that he only regarded red blood as
real blood; and probably did not suspect that there wa«

» E!/«/(t4«., kv»t(^»' Hist- Animal. 1. i. c. G.

DEFINITION OF THE TERM INSECT. 3

a true circulation in his Mollusca and other white-blooded
animals. His Enaima, or animals that have blood, he
divides into Qjiadntpcds, Birds^ Fishes, Cetacea, and
Apods or reptiles ; though he includes the latter, where
they have four legs, amongst the quadrupeds ^ ; and his
Anaima, or animals without blood, into Malachia, Ma-
lacostraca, Ostracoderma, and Entoma. The first of
these, the Malachia, he defines as animals that are ex-
ternally fleshy and internally soHd, like the Enaima; and
he gives the Sepia as the type of this class, which answers
to the Cephalopoda of the moderns. The next, the Ma-
lacostraca, synonymous with the Crustacea of Cuvier and
Lamarck, are those, he says, which have their solid part
without and die fleshy within, and whose shell will not
break, but sphts, upon collision Tlie Ostracoderma, cor-
responding with the Tcstacea of Linne, he also defines as
having their fleshy substance withm, and the solid with-
out; but whose shell, as to its fi-acture, reverses the cha-
racter of the Malacostraca. He defines his last class
Entoma, in Latin Lisecta, with which we are pruicipally
concerned, as animals whose body is distinguished by in-
cisures, either on its upper or under side, or on both, and
Jias no solid or fleshy substance separate, but something
intermediate, their body being equally hard both within
and without <=. This definition would include the Anne-
lida and most other Vervies of Linne, except the Testacea,
which accordingly were considered as msects by those
Zoologists that intervened between Aristotle and the lat-
ter author. The Stagyrite, however, in another place,

Hist. Animal. I. i. c. 5, 6 : compare 1. v. c. 3 and 83, and De
Partibiis Animal. 1. iv. c. 1 and 11.

Hist. Animal. 1. iv. c. 1.

B 2

DEFINITION OF THE TERM INSECT.

has expressly excluded all apods \ From other passages
in his works, it appears that he regarded the Vermes, &c.
either as larvce, or as produced spontaneously and not
.ex ovo^.

This definition of an insect, though partly founded on
misconception, as well as his primary division of animals
in general, is by no means contemptible. If you look at
a bee or a fly* you will observe at first sight that its body
is mscctech being divided as it were into three principal
pieces— head, trunk, and abdomen ; and if you examine
it more narrowly, you will find that the two last of these
parts, especially the abdomen, are further subdivided.
And this character of msection, or division into segments,
more or less present in ahiiost every insecf*, is not to be
found (with the exception of tlie Crustacea, which Ari-

» Evro,tt« 'TTohv'Kolx ,c*£v y«« £«■/ tuutu. De Part. Animal. 1. iv. C. G.
»" Hist. Ariimul. 1. iv. c. Ifl.

'■ The inscction that distinguishes these parts, the abdomen espe-
cially, is most visible in the majority of the Hymenoptera and Diptera
order's ; next in some Coleoptcra, as the Lamellimrn tribes, &c. and
the Lepidoptera. Latreille is of opinion, that the two last segments
of the thorax in some insects are represented by the first of the
abdomen, and that the upper half segment of this part in Coleoptcra
also represents the same. Latr. De quelques Appendices, &c. An-
nales Ghwrales dcs Sciences Physiques. A Bruxelles, vi. livrais. xviii.
14. In fact, in the Lepidoptera, when the abdomen is separated from
the trunk, this segment usually remains attached to the latter. In
the Myriapods. the trunk is to be distinguished from the abdomen
only by its bearing the three first pair of legs.

•> There is no general rule without exceptions, and no character is
so universal as to be distinctly exhibited by every member of a class
or other natural group. Thus, in the majority of the viites {Acarus
L.) the body is marked by no segments, and the only articulation or
incision is in the legs, palpi, &c. But as the exception does not make
void the rule, so neither does the extenuation or absence of some
primary character at its points of junction with others, in some indi-
viduals. auuihilate the class or group.

DEFINITION OF THK IT.RM J^^SEC7\

stotle distinguishes by the nature of their integninient
and its contents) in any of tlie other chisses into wliicli
he divided animals witliout blood. It was on account of
this most obvious of their characters, that these little
creatures were in Greek named Entoma^ and in Latin
Inseda ; and froni the former word, as you know, our
favourite science takes tlie name of Entomology.

Pliny adhering to the definition of Aristotle, as fur as
it relates to the inseciioti of the animals we are speaking
of, exjjressly includes ^y;o^/5, as well as Jjifera, amongst
them * ; and in this was followed, without any attenipt at'
improvement, by all die entomological writers that inter-
vened between him and the great Aristotle of the mo-
derns, ■ Linne.

This illustrious naturalist, aware of the incorrectness
of the primary divisions of the animal kingdom founded
upon the presence or absence of blood, establishes his
system upon the structure of the heart, and upon the
temperature and colour of the circulating fluid. He di-
vided animals into two great sections or sub-kingdoms,
each comprising tvvo classes. His Jrrsi section included
those having a heart with two ventricles, two auricles,
and warm and red blood, viz, the Mammalia or beasts,
and the Aves or birds. His sccohd, those having a heart
with one ventricle, one auricle, and cold and red blood,
namely, the classes Amphibia, which included reptiles,
serpents, &c. and Pisces or fish. His third, those hsi^ving
a heart with one ventricle and no auricle, and cold xvhite
sanies in the place of blood, namely, his classes Jnsccfa
et Vermes, including the Invcrfeln-atc aninials of La-

' Hist. Xal. 1. xi. c. I,

6 DEFINITION 01" THE TEIIM INSECT.

marck. Thus the first of Aristotle's great divisions he
increased by the addition of a new and very distinct class,
the Amphibia, by which some ground was gained in the
science ; but as much was lost by his compressing the
four classes of which the last consisted into two, by which
the natural classes of Cephalopoda and Crustacea merged
under Insecta and Vermes. Linne was not aware of the
extraordinary fact, that the Cephalopoda have three
hearts; and that though the Crustacea and Arachnida
have a circulation. Insects have none, or he would never
have taken this retrograde step.

Indeed Linne' s definition of an Insect is, in many
most material points, inapplicable, not only to the Crus-
tacea, but to many other animals included under that
denomination. This will appear evident from a very
slight exammation. Thus it runs : " Polypod animaU
cidct, hreathing hy lateral spiracles, armed every *where
\mth an osseous skin, whose head is furnished with mov-
able sensitive antennae^." Now of this definition only
the first member can be applied to the whole class which
it is meant to designate; for the entire genus Cancer L.,
which, with some others, forms the class Crustacea of the
moderns, does not respire by spiracles at all, but by gills ;
and the same in some degree may be said of spiders,
scorpions, &c. With the last member of the definition
Linne himself must have been aware that a large number
of what he conceived to be msects were at variance, as
mites, spiders, and many other of his apterous tribes :
though from some very recent observations of M. La-

» Animalcula pol3'pocla, spimciilh lateralibus respirantia, cute
ossea catapliracta ; antennis niobilibus seiisoriis instruuntur. Sj/sf.
Nat. ed. 12. i. 533,

DEFINITION Ol- THE TERM INSECT. 7

treille% there seems some ground for thinking, that in
these the antennae are represented by the mandibles,
palpi, &c.^ and to the soft flexible, coriaceous or mem-
branous skin of a vast number of insects, the term cutis
ossea is by no means applicable.

Evident as these incongruities are, when the Herculean
taskwliich Linne imposed upon himself, and the vastness
and variety of his labours, are considered, they become
very venial. Indeed, unless he had divided his class In-
secta into two or more, it was impossible to define it in-
telligibly to ordmary readers, otherwise than nearly in
the terms which he actually employed ; and these cha-
racters, restricted and amended by qualifymg clauses, are '
still those to which recurrence must be had in a popular
definition of the class, when separated as it ought to be
from the Crustacea and Arachnida.

Pennant, Brisson, and other zoologists, who, attending
to nature rather than system, saw the impropriety of unit-
ing a crab or a lobster in the same class with a bee or a
beetle, long since assigned the Crustacea their ancient
distinct rank. " But these changes," as Latreille ob-
serves " being only founded upon external characters,
might be deemed arbitrary ; and to fix our opinion, it
was necessary to have recourse to a decisive authority —
the intertial and comparative organization of these ani-

» Quoted by Mr, Wm. MacLeay in [his very remarkable and
learned work Jlora: Entomologiccs, in which he inclines to the same
opinion, 383.

^ Treviranus ( Uchcr den inncrn Ban der Arachniden, &c. 22.) al-
ways calls the palpi of spiders " Fulkorncr." In Scorpio he regards
them as palpi (Pa/pcn).

•= N. Did. d'Hisl. Nat. xvi. 181,

DKriNlTlON Oy THE TERM INSECT.

mals. It results from the observations of the most pro-
found comparative anatomist of our age, M. Cuvier, that
the Crustacea and Araclmida differ from insects properly
so called, and particularly from those that are furnished
with wings, in having a complete system of circulation,
a different mode of respiration, and that they have a more
perfect organization. Influenced by these motives, both
Cuvier and Lamarck have considered them as forming
two classes separate from insects. Treviranus, led by
considerations founded on the organs of circulation, of
respiration, and of generation, is of opinion that spiders
and scorpions ought to form one class with the Crustacea :
he observes, however, that the nervous system of all three
is very dissimilar ; and that in an arrangement founded ,
on this circumstance, the organs of motion, and the ex-
ternal shape, even spiders and scorpions must be placed
in different classes".

It is to be observed with regard to the Arachnida of
the French school, that the class as laid down by them
includes several animals that have .no circulation, and
breathe by trachece, of which description are the mites
{Acarus L.), and the harvest-men {Phalangium L.) &c.;
and therefore it has been divided into two orders, Pul-
monaria and Tracheana ; but if the definition from tlie
internal organization be adhered to, the latter should
either remain with the class Insecta, or form a new one by
themselves. Yet the animals that compose the Trachean
order of Arachnida, their external form considered, are
certainly much more nearly related to the spiders and

» Treviranus, ut supra, 48. For the nervous system of scorpions,
*ce /. i. /". 13 ; and for that of spiders, t. v./, lo.

DEFINITION OF THE TERM INSECT.

scorpions than to any members of the class Insecta at
present known. This circumstance, perhaps, may seem
to throw some doubt upon the modern system of classi-
fication.

I mustfurtlier observe, that the assertion of Treviraims,
which appears to intimate that the respiration ol' the pul-
monari) Arachnida is the same with that of the Crustacea^
is not quite correct, since in the latter the branchue or
gills are external, and in tlie former internal, the air en-
tering by spiracles before it acts upon them^<

It may not be amiss in this place to lay before you tlie
principal pomts in which the Crustacea and ylrachnida
agree with Insecta, and also those in which they differ.

The Crustacea agree with Insecta in having a body
divided into segments, furnished witlx jointed legs, com-
pound eyes, and antenna2. Their nervous system also is
not materially different, and they are both oviparous.
They differ from them in having the greater insections
of the body less strongly marked; in the greater num-
ber of legs on the trunk, the anterior ones perform-
ing the office of max ilia.'; in their eyes usually on a
moveable footstalk; dieir palpigerous mandibles; and
their four antennae at least in the great majority. But
the principal difference consists in the uiternal organi-
zation and the fountains of vitality; for the Crustacea have
a double circulation, die fountain of which is a heart in
the middle of their thorax^. They have tot) a kind of
gizzard and liver, at least the Decapods^, and their re-
spiration is by gills, Genuine ius(;cts terminate their

' Plate XXIX. Fig. 2. Trcviraniis, /. i. /l 1.
Ciuier Anat. Comp. iv. 407. " Did. fi'llisl. Xat, ix. 1J10.

DEFINITION or THE TERM INSECT.

existence after they have laid their eggs'"; but the Cnis-
tacea Hve longer, and lay more than once.

The Arachnida will be found to differ from insects
more widely than even the Crustacea. They agree in
their jointed legs and palpi ; immoveable eyes ; and in
being covered with a coriaceous or corneous integument:
but they differ in having a system of circulation; gills
instead of tracheae ; their organs of generation double ;
and the females lay more than once m their lives. Their
head also is not distinct from the trunk as in insects ;
they have no compound eyes ; and their antennas, if we
admit the opinion on this head of MM. Latreille and
Treviranus, that they have representatives of these or-
gans, differ totally in structure, situation, and use, from
those of the great body of insects. In the Araneidce or
Spiders, their body seems to have no segments or incisure
but that which separates the abdomen from the trunk ;
and in the Scorpmiidce they are observable only in the
abdomen. Other particulars might be enumerated hi
which these two classes differ from insects; but these will
be sufficient to convince you that Aristotle and MM. Cu-
vier and Lamarck were justified in separating them.

The two last-mentioned authors made further improve-
ments in Zoology. The latter, fi'om the consideration of
the general structure of animals, perceiving that Aristo-
tle's Enaima were distinguished from his Anaima, by
being built as it were upon a vertebral cohmm, very ju-
diciously changed the denomination, which was indeed
improper, of " The Philosopher' s'' two sub-kingdoms, mto

a The females of X>o;-//*e««, however, a genus related to Core,,,, arc
said to survive laying theb eggs. N. Did. d'lJist. XaL ix. 006.

DEFINITION OF THE TERM INSECT. U

that of Vertehrata or animals that have a vertebral co-
lumn, and Invertehrata or those that have no vertebral
column. These he distributes into three primary divi-
sions according to their supposed degrees of intelligence
—Thus:

* Ajmtheiic Animals. 1. Infusoria.

2. Polypi.

3. Radiata.

4. Vermes.

* * Sensitive Animals. - (Ejnzoaria.)

5. Insecta.

6. Arachnida.

7. Crustacea.

8. Annelida.

9. Cirrhipeda.

10. mollusca.
*** Intelligent Animals. 11. Pisces.

12. Reptilia.

13. AvES.

14. Mammalia. =^
Profiting by the light afforded by the Aristotelian sy-
stem, this eminent zoologist improved, we see, upon that
of Linne, by resolving his Insecta into three classes, and
his Va-mes into seven, interposing the Linnean Insecta
between the foui first and three last, in which he was
not so happy, since as to sense insects should certainly
occupy the place he has here assigned to the Mollusca.

In the work from which I have taken this statement
of Lamarck's system, that acute writer has given a sketch
of another method of arrangement, in which he has made
the first deviation from the beaten track of an unbroken

* An'm. sails Vcrlebr, i, 381.

12 DEFINITION or Tili: TERM INSECT.

and unbranchfiig series. In the Supplement to the first
volume, he has distributed the Invertehrata in a double
subramose series — one consisting of articulate, and the
other inarticulate animals '.

Upon Lamarck's system, most of the modern ones,
with some variation, are founded. There is one, how-
ever, by a learned countryman of ours, that is more
unique, sui generis, and I may add profound, than any
that has yet appeared. I am speaking of that, you will
perceive, of which our friend Mr. Wm. MacLeay has
given a detailed statement in his Hora Entomologiccc.-
In this he goes even far beyond what Lamarck has at-
tempted in the above sketch, and substantiates his claim
to be considered as one of those original thinkers, ran
nantes in gurgite vasto, that do not appear every day.
The following are the principal bases of his system.

1. That all natural groups, whether kingdoms or any
subdivision of them, return into themselves : a distribu-
tion which he expresses by circles.

2. That each of these circles is formed precisely of
five groups, each of which is resolvable into five other
smaller groups, and so on till you reach the extreme term
of such division.

3. That proximate circles or larger groups are con-
nected by the intervention of lesser groups, which he de-
nominates osculant.

4.. That there are relations of analogy between the
corresponding points of contiguous circles.

This system he has represented by tables of circles
inscribed'with the five primary divisions of each group.
His first table exhibits ii general view of organized matter

Anim. sanx Vertcbr, \. i^t.

DEFIXITIOK OF THE TERM mSECT. l-i

as distributed in the animal and vegetable kingdoms —
Tlius :

Our learned author here divides the animal kingdom
into what may be denominnted five sub-kingdoms or pro-
vinces, in three of which (with the exception of the Cms-
tacea and Arachnida belonging to his Atinidosa) no cir-
culation of blood is visible, but which obtains in the rest.
These he names —

1. AcuiTA, consisting of the Infusori/ AtiimalSj the
Polypi, the Corallines, the TaenicE, and the least organized
of tlie Intestinal Worms.

2. Radiata, including the Jelly-Jish, Star-Jish, Echini,
and some others.

3. Annulosa, consisting of Insecta, Arachnida, and
Crustacea.

4. Veutebrata, consisting of Beasts, Birds, Reptiles,
Amphibia, and Fishes.

5. MoLLUSCA, including the numerous tribes of shell-
fish, land-shells, shigs, &c., which, from their mucous or
gelatinous substance, from their nervous system and the
imperfection of their senses, return again to the Acrita,

DEFINITION OF THE TERM INSECT.

though connected with tlie Vertehrata by having a heart
and circulation.

His next set of circles shows the sub-division of these
five sub-kingdoms into classes — Thus :

In this scheme the osculant classes are those placed
between the circles. In the Mollusca circle two classes
are still wanting to complete the quinary arrangement
of that sub-kingdom. I am not sufficiently conversant

DEFINITION OF THE TERM INSECT.

with the details of the animal kingdom at large to hazard
any decided opinion upon Mr. MacLeay's whole system,
or to ascertain whedier all these classes are sufficiently
distinct My sentiments with i-egard to tliose of die
Anmilosa I shall state to you hereafter.

Upon a future occasion I shall consider more at large
the station to which insects seem entitled in a system of
invertebrate animals, which will not accord exactly with
that assigned by MM. Cuvier and Lamarck. But I am
now m a field in which I have no intention to expatiate
further, than as it is connected with the subject of the
present letter. I shall therefore" confine myself in what
I have more to say to ther definitions of Insccta that have
been given by modern authors, begimiing with that of
the zoologist last mentioned. Insects form a part of his
secojid group, which he terms sensitive animals [animaux

sensihles\ which group he thus defines : " They are sen-
ticnti hut obtain from their sensations only paxeptions
of objects — a Iciiid of simple ideas 'which they cannot
combine to obtain complex ones. Charact. No va-tebral
column ; a brai7i, and most commonly an elongated me-
dullary mass : some distinct senses the organs of move-
ment attached wider the skin: fm-m symmetrical, by
parts, inpairs^." This division of animals, fi'om the

■* The number five, which Mr. MacLeay assumes for one basis of
his system as consecrated in Nature, seems to me to yield to the
number seven, which is consecrated both in Nature and Scripture.
Metaphysicians reckon seveii principal operations of the mind ; mu-
sicians seven principal musical tonesj and opticians seven primary
colours. In Scripture the abstract idea of this number is — comj^le-
tion—f ullness — perfection. I have a notion, but not yet sufficiently
matured, that Mr. MacLeay's quinaries are resolvable into scptenai-ies.
Anbn.sans Vcrtcbr.'u 381.

16 DEFINITION OF THK TERM I^^SECT.

kind and degree of sense and intelligence that they pos-
sess, seems rather fanciful than founded in nature, since
many insects show a greater portion of them than many
vertebrate animals. Compare in this respect a bee with
a tortoise''. Lamarck divides his group ofanimaux seti-
sibles into two sections, namely, Artiailated animals, ex-
hibiting segments or articulations in all or some of dieir
parts ; and Inartimlated animals, exhibiting neither seg-
ments nor articulations in any of their parts. Insecta,
Arachnicla,' and Crustacea, belong to the first of these
sections, which he defines as " those u^hose body is di-
vided into segments, and which are furnished with jointed
less bent at the articulations^" Insecta he defines—
*' Articulate animals, undergoing various metamorphoses,
or acqniri7ig new kinds of parts^having, in their perfect
state, six feet, two antcnnce, two compo^md eyes, and a
corneous skin. The majority acquiring wings. Respira-
tion by spiracles (stigmates), and two vascular opposite
chords, divided by plexus, and constituting aeriferous tra-
chea:, which extend every where. A small brain at the
anterior extremity of a longitudinal knotty marrow, with
nerves. No system of circulation, no conglomerate glands.
Generation oviparom : two distinct sexes. A single sex-
ual union in the whole course ofUfe^." Arachnida he
defines—" Oviparous animaU, havitig at all times jointed
legs, undergoing no metamorphosis, and never acquiring
new kinds of parts. Respiration tracheal or branchial :
the openings fo)- the entra7ice of the air spiraculiform
[stigmatiformes). A heart and circulation beginning in

^ See on tl>is point MacLeuy, Ilor. Enhmolog. 209~.
- Aiiini. .mis Verlehr. iii. 24:5. 1^''<^'

DEFINITION OF THE TERM INSECT.

ma7ii/. The inajority couple often in the course oflifc^."
I shall next add his definition of Crustacea : " Ovipa-
rous, artimlated, apterous animals, 'with a mistaceous in-
tegument more or less solid, having jointed legs ei/es
either pedunculate or sessile, and most coinmonly four
antennce, xvith a maxillifercms mouth seldom rostriform ;
maxillce in many pairs placed one ovei' the other ; scarcely
any under-lip no spiraculifmm openings for respiration ;
five or seven pair of legs ; a longitudinal knotty marrois)
tei-minated anteiiorly by a small brain. A heart and ves-
sels for circidation. Respiration h-anchial isoith extei-nal
branchicc, sometimes hid under the sides of the shell of the
thorax, or shut in prominent parts sometimes uncovered,
and in general adhering to partiadar legs or to the tail^
Each sex usually double^ J'

I have given Lamarck's definitions of these three classes,
all considered as Insecta by Linne, that by comparing
them together you may be better enabled to appreciate
the system of this author. On looking over the characters
of the Arachnida as here given, you will see at once that
it consists of heterogeneous animals— for in fact he in-
cludes in this class not only the Trachean Arachnida of
Latreille, but the Ametabolia of Dr. Leach, or the Hexa-
pod Aptera, and the Myriapoda.

I shall next copy for you Latreille's latest definition of
Insecta and Arachnida.

" Insecta : A single dorsal vessel representing the
heart: two trunks of trachea ru7ining the whole length
of the body, and opening externally In/ numerous spira-
cles; two antenncs; very often uppei- appendages for
flight, indicating the metamorphosis to which the animal

Auim. sam Vcrtebr. m. 245. t /^jrf.

VOL. III. P

18 DEFINITION OF THE TERM INSECT.

is subject When young ; legs most commonly reduced to
six Arachnida: Distinguished from Crustacea by
having their respiratory mgans always internal, opening
on the sides of the abdomen or- thm-ax to receive the re-
spirablefuid. Sometimes these mgans perform the office
of lungs, and then the circulation takes place by means oj
a dorsal vessel, which sends fm-th arterial, and receives
venose branches. Sometimes they are trachecB or air-
vessels, which, as in the class Insecta, replace those of
ch-culation. These have only the vestige of a heart, or a
dorsal vessel alternately contracting and sending forth
no branch. The absence of antennae, the reunion of the
head with the thorax, a simple trachea but ramified and
almost radiating, serve to di^inguish these last Arachmda,
or tKe most imperfect of insects, which respire oidy by
trachea^." Under this head he observes-' Ot all
these characters, the most easy to seize and the most
certain would doubtless be, if there were no mistake m it,
that of the absence of antennae; but later and compara-
tive researches, confirmed by analogy, have convinced
me, that these organs, under particular modifications it
is true, and which have misled the attention of naturalists,
do exist-" and he supposes, from the situation and di-
rection of the mandibles of the Arachnida, correspondmg
with that of the intermediate pair of antennce \Macea,
that they really represent the latter organs. If this sup-
positionbeadmitted, their use iswholly changed; thepalpi,

in fact, executing the functions of antennae, which proba-
bly induced Treviranus to call them Fmhorner ^Feeling-

^ ' At rles Anim. inverlebr. aiiic, Ann. du

a Des Rapports generatix, (!{C. aes nmm.

Mux.

b Ibid. IIoi: Eiitomolog. 38J.

DEFINITION OF THE TERM IXSECT. 19

horns). Perhaps tliese last may be regarded as in some
sort representing the external antennae of the Crustacea ?
With regard to Insecta^ tlieir antennae seem to disappear
in the Pupipara Latr., or the genus Hippobosca L.

The above definitions of the Arachnida by these two
celebrated authors, appear to me the reverse of satisfac-
tory. When we are told of animals included in it, that
some breathe by gills and others by tracheae, that some
have a heart and circulation and others not, we are im-
mediately struck by the incongruity^, and are led to sus-
pect that animals differing so widely in the fountains of
life ought not to be associated in the same class. A
learned zoologist of our own country, Dr. Leach, seems
to have made a nearer approach to a classification in ac-
cordance with the internal organization, by excluding
from Arachnida the Acari and Myriapoda.

Sub-kingdom Annulata Cuv.

* Gills for respiration. Classes.
Legs sixteen: .... Antennae two or four 1 Crustacea.

** Sacs for respiration.
Legshuelve: .... Antennas none 3 Akachnoidea.

*** Tracheae for respiration.

a. No Antennae.

4 Acari.

b. Two Antennae.

Six thoracic legs : Abdomen also bearing legs 2 Myriapoda.

Sir thoracic legs : No abdominal legs 5 Insecta\

Mr. MacLeay, on whose system I shall now say a few
words, divides his sub-kingdom Anmdosa into five classes,
namely, Cmstacea, Avietabola, Mandibulata, Hamtellata,
Arachnida. From the Cnistacea he goes by the genus

» Leach in Entomologist's Useful Compendium, hy SamoueUe, 75.

c 2

20 DEFINITION OF THE TERM INSECT.

Porcemo Latv. to Iulus\ which begins his Ametahola:
these he connects with the Mandibulata, by Nirmus,
which he thinks approaches some of the corticarious
Coleoptera^. This class he appears to leave by the Tn-
cJioptera Kirby, and so enters his Haustellata by theZ.^-
pidoptera'^, and leaves it again by the Diptera by means
of the Pupiparce Latr., especiaUy Nycterihia, connectuig
this class with the Arachnida, which he enters by the
Hexapod Acari L/, and these last he appears to leave
by the Araneidce, and to enter the Crustacea by the De-
capods^: thus making good his circle of classes, or a
series of Annulose animals returnmg into itself. Mr.
MacLeay's whole system upon paper appears very har-
monious and consistent, and bears a most seducing aspect
of verisimilitude; but it has not yet been so thoroughly
weighed, discussed, and sifted, as to justify our adoptmg
it in toto at present: should it, however, upon an impartial
and thorough investigation, come forth from the furnace
as gold, and be found to correspond with the actual state
of Slings in nature, my objections, which rest only upon
some parts of his arrangement of Annulosa, would soon
vanish. Some of those objections I will state here, and
some will come in better when I treat of the Systems
of Entomology. My first objection is, that his Ameta-
hola, Mandibidata, and Haustellata, approach much
nearer to each other than they do to the other two classes
. of his circle, or than even these last to each other ; so
that under this view it should prhnarily consist three
<rreater groups, resolvable, it may be, into five smaller
ones. My next objection is, that he has also considered

a Entouolog. 348. " Ibid. 354. Ibid. 373.

J Thid.3%\. " Ib'd.^H^.

DEFINITION OF THE TERM INSECT. 21

the Trachean and Pulmonarxj Arachnida as forming one
class. Whether an animal breathes by gills or trachea,
or has a circulation or not, is surely as strong a reason
for considering those so distinguished as belonging to dif-
ferent classes, as the taking of their food by suction or by
manducation is, for separating others to the full as much
or more nearly related as to their external structure.
But of this more hereafter. I cannot help, as a last ob-
jection, lamenting that our learned author has rejected
from his system a term consecrated from the most remote
antiquity, and which, even admitting his arrangement,
might have been substituted for Annulosa, a name bor-
rowed by Scaliger from Albertus Magnus, neither of
whom, in Entomology, is an authority to weigh against
Aristotle, from whom we derive the terra Insecta^ in
Greek EvTOfx-a.

As Fabricius did not alter Linne's class Insecta, but
merely broke up his orders into new ones, which he
named classes, I shall give you a detail of the alterations
he introduced into the science in a future letter.

Having stated what my predecessors have done in
classification, I shall next proceed to lay before you my
own sentiments as to^ JV/iaf is an insect. Since our
correspondence commenced, the Arachnida, principally
on account of their internal organization, have been ex-
cluded from bearing that name, carrying with them, as
we have seen, several tribes, which as yet have not
been discovered to differ materially in that respect from
the present Insecta for the sake, therefore, of conve-
nience and consistency, that I may, as far as the case
will admit, adhere to the Horatian maxim

Servetur ad imum

Qualis ab inccpto proccsscrit et sibi constet,

22 DEFINITION QF THE TERM INSECT.

I shall regard as Insects all those Annulosa that respire
by tracheae and have no chculation, considering the
Trachean Arachnida and the Myriapoda for the present
as sub-classes, the one bordering upon Arachnida,Q.nd.
the other upon the Crustacea. Some of these I am ready
to own seem separated by an interval sufficiently wide
from the Hexapods, which may be regarded as more pe-
culiarly entitled to the denomination of Insects. The
most striking differences will be found in the coalition of
the head with the trunk in some {Phalangida), and the
disappearance of the annulose form of the body in others
{Acarus L.), so that the legs only are jointed". Yet an
» There is some reason for thinking, though the octopod and my-
riapod insects breathe by tracheae, that there is no small difference in
tlw distribution of these organs. The Trachean Arachnida h^xe only
a pair of spiracles, from which the tracheae must radiate, it 1 may so
apply the term, in order to convey the necessary supply of air to every
part of the body. Sczdigera, as far as I can discover, has only a single
series of dorsal spiracles (see Plate XXIX.Fig. 20)-an unusual situ-
ation for them : in these also, to attain the above end, each tracnea
must also radiate, so as to supply each part of the segment it is m.
Those o( licks, according to the observations of Savi (Osservaz. per
servire alia Storia di una Specie de IidusM- consist of bundles

of parallel tracheae. Perhaps these circumstances would warrant the
considering oHhe^e Arachnida and the Myriapoda as primary classes.
The genus Galeodes is said to breathe by gUls similar to those ot the
AraneidcB, which structure, probablj', carries with it a system ot cir-
culation, and exhibits a third type in the Arachnida,ysith four palpi,
six legs, and a distinct thorax. This genus, then, is the corresponding
point in the Arachnida to the He.vapod Aptera, as the Scorpions are
to the Cheliferid^ or Pseudo-Scorpions, and the Araneid^ to the otlier
Octopods; and these analogies furnish a strong proof; that the Ira-
cheans belong rather to Insecta than Arachnida Comp. A. UKt.
d'Hist. Nat. xxvi. 445; and Description de sic Arachnid, nouv. &c.

par Leon Dufour, 16. , j j„

b Mr MacLeay observes with regard to the Tardigrade, de-
scribed by Spallanzani and Dutrochet, that " it proves that an animal
may exist without antennee or distinct annu ar segments to th|
but having two eyes and six articulate legs." (HorMomolog. 3o0- .)
Many Acari prove the same thing. De Gcer, vn. /. vu./. i^-

DEFINITION OF THE TERM INSECT.

approach to such structure may be traced in some Hexa-
pods ; for instance, the coalition of the head and trunk
in Melophagus, Latr., and that of the trunk and abdomen
in Sminthurus, Latr. * The Myriapoda exhibit other re-
markable differences ; though their head and trunk are
distinct, the former antenniferous, and their body annu-
lose, the abdomen as well as the trunk is furnished with
legs, sometimes amounting to hundreds ; but even to this
a tendency has been observed in some Hexapods''. If
you examine a specimen of Machilis polypoda, an insect
related to the common sugar-louse {Lepisvia saccharina)*
you will find that the abdomen is furnished with a double
series of elastic appendages, which, being instruments of
motion, may be regarded as representing legs. It is
worthy of notice, that the Myriapoda when first disclosed
from the egg have never more than six legs and keep
acquiring additional pairs of them and additional seg-
ments to their abdomen as they change their skins : and
it is equally remarkable, that many Hexapods are subject
. to a law in some degree the very reverse of this, having
many abdomuial legs in their first state, and losing them
all in their last. The union of the head with the trunk
in the Trachean Arachnida has been regarded as almost
an unanswerable argument, in spite of their different in-
ternal organization, for including them in the same class
with the Ptdmonary Arachnida • but the case of Galeodes,
which, though furnished with gills, (as an eminent Rus-
sian Entomologist Dr. G. Fischer is reported to have
' discovered,) implying also a circulation, and evidently
belonging to the last-mentioned class, has nevertheless a
distinct thorax consisting of more than one piece, to which

" De Gecr, vii. /. iii./. 8, >> Hor. Enlomolog. 351

DeGeer, Ibid. 571, 583, I. xxxvi,/. 20, 21.

24 DEFINITION OF THE TERM INSECT-

are affixed only six legs% proves that even this circum-
stance possesses no weight when set against the organi-
zation. If it was a difference in this respect, that proved
the Crustacea classically distinct from Insecta—t\\at like-
wise was the principal reason for the separation also of
the Arachnida—it seems to follow that it ought also to
furnish an argument equally cogent for considering the
Trachean Arac/mida, as well as the Myriapoda, distinct
from the Pidmonary,

Another difference between the tribes in question is
that of \h€\v metamorphosis : and this appears to have
had great weight with Lamarck, inducing him to mclude
in his Arachnida, not only the Tracheans and Myriapods,
but even the apterous Hexapods, except Pidex, or the
Anoplura and Thysanura of modern authors. But the
metamorphosis alone, unless supported by the internal
organization, will I think scarcely be deemed a sufficient
reason for separating from each other tribes agreeing in
that respect, and placing them with others with which
they disagree. The metamorphosis in some of the Hex-
apods {Lepidoptera) consists in the loss of legs, the ac-
quisition of wings, a great change in the oral organs and
in the general form; in others (some Coleoptera), in the
acquisition only of wings and a change of shape, the oral
organs remaining much the same; in others again {Otr-
mlio L.), in the acquisition of six legs and wings and a
change of form; in the flea, in the acquisition of six
legs and a change of form only ; in the Orthoptera, He-
miptera, &c. in the mere acquisition of wings; in the
Lihellulidcr, in the loss of the mask that covers the mouth
and the acquisition of wings; in the Diptera, in the ao-
Dufoiir nbi supra, Hor. Enlomolog. 3Si.

DEFINITION OF THE TERM INSECT. 25

quisition of six legs, wings, a change of the oral organs
and of the form ; in some of the Octopods {Acarus L.),
in the acquisition of a pair of legs ; and in others {Pha-
langmm and Aranea L.)? solely in a modification of them
as to their proportions ; in the Myriapods, the alteration
that takes place in this respect is considerable ; a large
number of pairs of legs is acquired and many additional
abdominal segments, and the proportion which the ab-
domen bears to the whole insect is quite altered. In all
these cases there is a change more or less, either partial
or general, of the original shape or organs of the animal ;
and with regard to their metamorphosis, there is a greater
difference between a young and adult Iidus than between
a young and A&vih, grasshoppei' or bug: so that if die meta-
morphosis, per se, be assumed as a principal regulator of
the class, the grasshopper or bug have as little claim to
belong to it as the Itdus.

M. Lamarck lays considerable stress upon another
character — That Insecta engender only once in the course
of their lives, and AracJmida more than once. But this,
if examined, will be fomid to be confined chiefly to the
Puhnonary A^'achnida^ the Tracheans following the law
of Insecta in this respect*.

You may perhaps object that the bringing of the Tra--
chean Arachnida and the Myriapoda into the class Jn-
secta will render the approximation of them to a natural
arrangement more difficult, since it will be impossible
at the same time to connect the Myriapods with the
Cnistacea, and the Tracheaii with the genuine Arachnida.

* Male Insecta in some instances engender more than once. Mr.
MacLeay sen. has observed this with regard to Ckrysomela Poh/goni,
and I have nolitcd it in Bvmbi/x Mori.

26 DEFINITION OF THE TERM INSECT.

I admit the validity of your objection, but by no arrange-
ment of insects in a simple series can we attain this object :
the difficulty, however, may perhaps be obviated in this
way. The distribution of organized matter, to adopt
Mr. Wm. MacLeay's metaphor*, begms in a dichotomy,
constituting the animal and vegetable branches of the
great tree of nature, and from these two great branches, by
means of infinite ramifications, the whole system is form-
ed, and, what is remarkable, these branches unite again
so as to represent a series returning into itself, a disco-
very due to the patient investigation and acumen of our
learned friend just mentioned. Now, in considering
the Aptera order, we find at first setting out from the
Hexapods, a dichotomy, where the Anoplura Leach
branch off on the one side, and the Tkysanura Latr. on
the other — the former, by means of the Pediculidce, tak-
ing their food by suction, particularly Phthirus Leach,
or the Morpion (in which the segments of the trunk and
abdomen become indistinct'') approach the Octopods by
the hexapod Acari L.— the latter by Machilis polypoda
tending towards the Myriapods. In the Octopod branch
a further dichotomy takes place, from which you proceed
on one side to the Araneidce in the Arac/mida, by Pha-
langium, &c. ; and in the other by Chelifer, &c. to Scwpio.
Again, the Myriapod branch also divides, going by the
lulidce to one branch oith&Isopod Crustacea, and by the
Scolopendridce to another.

But there is another view of this subject before alluded
,to, which may be repeated here, and which seems to

» Hor. Entomolog. 134. 200.

" Zoolag. MiscelL iii. t. 146. In tliis figure the segments are
made much more distinct than they are in my specimen.

DEFINITION OF THE TEIIM INSECT. 27

prove that the types of form in one natural group or
class are reproduced in another ; this appears to result
from the following parallel series :

Nturopterous Aptera. Arachnida. Crustacea.

Larva;.

Psocus Hexapoda Galeodes Larimda.

Myrmeleon Phalangium. . . . Aranea | ^chyunu*

Octopoda rDecapoda nia-

c • J croura. T/ia-
Panorpa ? C/ic/ifer Scorpio. . . . < ^^^^^ g^^^.^

V especially.

Ephemera Myriapoda ***** Isopoda.

No type representing the Myriapoda has yet been
discovered in the Arachnida class; but I have little
doubt of its existence. You will observe that the ana-
logies between the larvae of the mnged orders and the
Aptera were first noticed by Mr. W. MacLeay*. It is
probable that these parallel series of representatives of
each other might be increased, as well as the numbers in
the respective columns.

What I have said will, I trust, sufficiently justify me
for making at present no more material alterations in tlie
classification I long since proposed to you''; I shall,
therefore, now proceed to define the objects I consider as
Jnsecta; but I shall first observe — that as Latreille con-
siders the h'anchiopod Crustacea or E^itomostraca of
Miiller as entitled to the denomination of Crustaceo-
ylrac/mida^ J so his Trachean Arachnida might be called
Arachnido-Insecta, and his Myriapoda^ Crusiaceo-Insecia.

» Hor. Enlomolog. 42iJ— .

^ See above, Vol. I. 4th Ed. p. 66. Note ».

<^ Surely the denomination ought to have heenAraclmido-Crustacea,
since the learned author considers them as belonging to the Crustacea
class.

28 DEFINITION OF THE TERM INSECT.

Sub-ki?igdom — Annulosa
Class — Insecta.
First Definition— From their external Organization.
Body— divided into Head — Trunk — Abdomen.

Head. — Principal seat of the organs of sensation.

Organs of sight. Immoveable eyes, simple or com-
pound, varying in number.

Organs of hearing uncertain, probably connected
with the antennae.

Organ of taste. Ligula or pa]ate within the mouth,
accompanied by the organs of manducation — a pair
of mandibles and maxillaa and an upper and lower
lip, or their representatives.

Organs of touch. Prmcipally two jointed antennae
or their representatives, and four jointed feelers —
two maxillary and two labial.
Trunk. Principal seat of the organs of motion.

Organs of voalking, running, or jumping. Six or
eight jomted thoracic legs, in pairs.

Organs of fight. Four wings or their representa-

a It may not be without use to give here a short definition of the
Annulosa; I mean excluding the Vermes, which Mr. W MacLeay
has induded; and the Annelida, which Latreille has made the filth
of his Annulose classes. Ann. du Mus.\%'^\.

Annulosa. Animal invertebrate, oviparous j external mtegumentot
a firmer consistence than the internal substance, sen'ing
as a general point of attaclnnent to the muscles; cijcs
immoveable; legs more than four, jointed.

1. Cnistacea. Gills external ; more than eight legs.
% Arachnidn. Gills internal ; spiracles ; eight legs.
3. Insecta. Trachea; j spiracles; six to eight thoracic legs.

DEFINITION OF THE TERM INSECT.

tives, mostly with branching nervures containing
air-vessels ; found in the majority of the class.
Organs {exteryial) of respiration. A double set of
lateral spiracles, some for expiration.

Abdomen. Principal seat of the organs of generation.
Oi-gans of motion. In the Myriapods many pairs

of acquired legs ; in the Thysanura elastic ventral

or caudal appendages.
Organs of respiration. A double series of lateral

spiracles for inspiration in the majority : in some

only a single series, and in others only a single

pair.

Organs of generation those common to the Ver-
teh-ata, but retractile within the body, attended
usually by various anal appendages, particularly
a forceps in the males, and an ovipositor in the
females.

Second Definition — From their internal Organization.
Sensation.

Nervous System. A small brain usually subbilobed,
crowning a knotty double medullary chord ; nerves
proceedmg fi-om the brain and other ganglions to
all parts of the body.
Circulation.

Heart replaced by a simple alternately contracting
dorsal vessel or pseudocordia, without arteries or
veins, but filled with a white cold sanies.
Respiration.

Lungs replaced by tracheae, which receive the air
from the spiracles, and distribute it by bvonchias
infinitely ramified.

DEFINITION OF THE TERM INSECT.

Digestion.

Liver and biliary vessels in most replaced by from
2 to + 150 floating hepatic filaments opening into
the space between the two skins of the intestinal
canal below the pylorus.
Generation.

Internal organs. Males — Vasa deferentia, and vesi-
culse seminales, and the other ordinary organs. Fe-
males—Ovoxj usually bipartite, with palmate lobes;
genital organs single and mostly anal ; one sexual
union impregnates the female for her hfe.
Develojrment. In their passage to their adult state,
after they have left the egg, insects undergo several si-
multaneous changes of their integument or successive
moults, and the majority assume three distinct forms,
with distinct organs, which appear as rudiments in their
second state, and are completely developed in their last.

In defining the Arachnida I shall only mention those
particulars m which they differ from Bisecta in their ex-
ternal anatomy.

Class — Arachnida.

Body.

Head and Trunk usually not separated by a suture.
Eyes. Two to eight, not lateral.
Mandibles cheliform or unguiculate, representing
the interior pair of the antennae of die Crustacea.
Palpi pediform or cheliform.
Trunk. Legs eight or their representatives: tibiae
mostly consisting of two joints.
Abdomen with from two to eight spiracles.

DEFINITION OF THE TERM INSECT.

Sensation.

Nervmis System. A small bilobed brain cro\vning a
double, knotty, medullary chord; nerves proceeding
from the brain and other ganglions to all parts of
the body.
Circulation.
Heart unilocular, inaurite, with a system of circulation
by arteries and veins ; blood a cold white sanies.
Respiration.

Lungs replaced by internal gills receiving the air by
spiracles.
Digestion.

L.ivei\ consisting of conglomerate glands, and enve-
loping the intestines ^ ; hepatic ducts.
Generation.

Genital organs double, ventral ; more than one sexual
union in the course of life.

Tlie external characters in this class are the same al-
most in every respect as those which distinguish the
Phalangidce, the whole difference consisting almost in
the systems of circulation, respiration, and digestion.
Perhaps some future anatomist may discover in the tribe
just mentioned, that there is a nearer agreement between
them and the Arachnida in these systems than is at pre-
sent suspected, which would prove them true Arachnida.
I am inclined to think that Phrynus and Gonyle^tes^ &c.
breathe by branchial spiracles; but having no opportu-

* What L. Dufour regards as the liver in Scorpio (iV. Diet. d'Hist.
Nat. XXX. 451.) Treviranus looks upon as an Epiploon {Fettkorper)
both in Scorpio and Aranea. 6. t. \.f. 6. A A. t. W.f. 24. dd. Hepatic
ducts: I. If. 6. ii. t. ilf. 24. fi.fi. fi. (i.

32 DEFINITION OF THE TERM INSECT.

tunity of examining living specimens, I dare not speak
with any confidence on tlie subject.

Having thus given you a view of the most impoi-tant
diagnostics by which what we have all along called In-
sects may scientifically be distinguished from other inver-
tebrate animals, it may not be without use, if, under
this head, I take a more popular and familiar view of
the subject, and say something upon those distinctions
which may attract the attention of the more common
observer.

The notion of diminutive size, particularly as com-
pared with vertebrate animals, seems more frequently
attached to the idea of an insect than any other; and
this notion is generally correct, for one insect that is
bigger than the least of the above animals, thousands
and" thousands are vastly smaller : but there exist some
that are considerably larger, whether we take length or
bulk into consideration, and this in almost every order.
To prove this most effectually, and that you may have a
synoptical view of the comparative size of the larger
insects of the different orders and tribes, I now lay be-
fore you a table of the dimensions of such of the largest
as I have had an opportunity of measuring, including
particularly those giants that are natives of the British
isles.

DEFINITrON OF THE TERM INSECT.

-< OJ CM ^ ^

fc
53

■ftfcc Hoc «|M< H»i "H Hfi '"h -Icq h4 ""I-S

•<j< 06

^1= J'=>

-I cjq 00 r-c

r-
O
►J

•SO

^ to

O ^

.=o

Q
P

q ii;

»3

^ i -

Q :^ s

- >5 <;

u < o

o
Q

'/i ffi P3

Co &o

Q
H

« <o

.§0 g
3 ^

• 3

Q
« as

< w

Co
S

YCE

vol.. JU.

DEFINITION OF THE TEUM IXSECT.

8 C

K •
•I

••-4 c
fid tyoi-*
^ s
o

Si ^

eg-

*i-H cdoo i.'slco
CM

c a

J3
o

i-c;
H

a
o

(J Co

•A

to
o

be
to

to
to

Q
■J

03
>^
OS

CV. ^

H*> H<» ■

^ 3 31

Is I
C5<j 00 CC

!/5

P. H

H
O

h3 O X W W

<1
Pi

o
a:

S «

.b.|

DEFIXITroX OF THE TEIl.Ar INSECT.

.10

if5

H»i Him H^i
CO 00 CO

"-i CN

^ ^

CO <N CM

CO 0^

0< I— I r-l 01

!Z5

s
o

Ci ft.

N
C3

65
Q

O
O

o
o
>^

o — ,

Q
<

* 6^

* 2

u 2

• w

S o

* d

^ H

£3

12;

O *

2 *
s

a.
C/3

DEFINITION OF THE TERM INSECT.

l£5 f-i M

n)-^ rJfii
00 i« O

fcifl -a
S3 a

-I-* '-'I'*
CM I— I I— (

CO*

^ *

Q «

'C T3 f3 '13

>0 CO 01 C-l c<>

5^ 8

b 2

ccJ

^ O Q

(M i-i

•

I-}

8
8

to
s

C>2 ft-

o
o

d Q 8 »i
S: S 2 w

.° ^ .5 a.

DEFINITION OF THE TERM JNHECT.

6c rJ!

• 5 'CO

go >-i
o

i =
I— (

e^-* Hoo

(I)

»5

• &

^ g 2

Q a a

d 2 «

<^ S H

H
Oh

<! fa *

e5 * o * Q

u
CO

• "is

O
<

03
U

02 02

J?; 12;

ST" bo

»^ ^ Pi <!
O <5

63
Q

5
O

o
u

DEFINITION OF THE TEll.M INSECT.

From this table you see that several insects included
in it exceed some of the smallest Vcrtebrata in bulk. In
the Mammalia^ the Sorex Arancus, called by the common
people here the Ranny, is not more than two inches
long excluding the tail ; and the Mus messorius, or har-
vest-mouse, peculiar to the southern counties of England,
is still more diminutive : so that to these little animals,
the larger Dynastidce, Goliathi, and Prioni, &c., appear
giants, and may compete with the mole in size. Even some
of the beetles of our own country, as the gi-eat Hydrophi-
lus, the stag-beetle, &c., are more bulky than the two
first-named quadrupeds. Amongst the birds, many Pic^e,
Passeres, &c., yield to several insects in dunensions, and
their wings when expanded do not extend so far as those
of not a few Lepidoptera. The great owl-moth of Brazil
{Erebus Strix) in this respect is a larger fowl than the
quail. Those beautiful little creaturesj the humming-
birds {Trochilus L.), the pecuhar ornament and life of
tropical gardens, which emulate the most splendid but-
terflies in the brilKancy of their plumage, are smaller
than a considerable number of insects in almost every
order, and even than some of those that are natives of
Britain. Various reptiles also are much inferior in size
to many of the msects of the above table. The smallest
lizard of this country would be outweighed by tlie great
British beetles lately mentioned, and the mole-cricket
{Gryllotalpa mlgaris); and some of the serpent tribe are
smaller than the larger Scolojjendra and ML Amongst
the Jshes also, though some are so enormous in bulk,
others in this respect yield the palm to several insects.
The minnow and the sticJcleback that frequent our own
pools and streams are considerably inferior in size to
some of our water beetles.

DEFINlTlOxV OF THE TERM INSECT. M)

In looking over the table, and comparing the different
species that compose it with each other, you will perceive
that the largest insects of the two sections Hemiptera,
of the Lepidoptera as to their body merely, of the Hy-
menoptera and Diptera, in general size tall considerably
short of those of the other orders; and that certain mdi-
viduals of the Orthoptera and Apto-a bear away the
palm in this respect from all the rest. In the Coleoptera
the giants, with the exception of the Goliathi, are chiefly
to be found amongst the timber devourers in the Lamel-
licorn and Capricorn tribes. Of orthopterous insects the
PhasmidcB present the most strikmg examples oimagrii-
tude; and in the Neuroptera, the Jgrionida of great
length.

It is worthy of remark here, that although the tropical
species of a genus usually exceed those of colder chmates
in size, the Gtyllotalpa of Brazil is very considerably
smaller than that of Europe : whether this is the case
with the rest of the cricket tribe I have not had an op-
portunity of ascertaining. The Lepidoptera^ though often
remarkable for the vast expansion of their " sail-broad
vans," if you consider only their bodies, never attain to
gigantic bulk. Even the hawk-moths {Sphinx L.), though
usually very robust, make no approach to the size of
the great beetles, or the length of some of the specti-es
{Phasma) and dragon-flies (Agrionidce). With regard
to the superficial contents of their wings, a considerable
difference obtains in different species where they expand
to the same length — for the secondary wings are some-
times smaller than theprimary, and sometimes they equal
them in size. In some instances, also, the latter although
long are narrow, and in others they are nearly as wide
as long : regard, therefore, should be had to their ex-

DEFINITION OF THE TERM INSECT.

pansion both ways. In the Hijmeno-piera and Diptera^
the principal giants are to be found in the predaceous or
blood-sucking tribes, as ScoUa, the Sphecidce, Pompilida,
Vespidce, &c., belonging to the former order; and the
AsilidcE and Tahanidce to the latter. The ti'ue and false
humble bees [Bomhus and Xylocopa) and the fly tribe
[Miiscida), though they sometimes attain to considerable
size, scarcely afford an exception to this observation.
Amongst the Aptera none of the Hexapods strike us by
their magnitude, and few of the Octopods, though the
legs of some of the Phalangidce inclose a vast area. That
in the table would with them describe a circle of six
inches diameter, though its body is little more than a
quarter of an inch in length. The Myriapods exceed
most insects in the vast elongation of their body, which
with their motion gives them no slight resemblance to
the serpents. In the class Arachnida, the bird-spiders
( Ml/gale) are amongst the principal giants, nor do the
Scorpiojis fall far short of them — both of them when alive
often alarming the beholder as much by their size as by
their aspect.

But as I have before observed, generally speaking, one
of the most remarkable characters of the insect world, is
the little space they occupy ; for though they touch the
vertebrate animals and even quadrupeds by their giants,
yet more commonly in this feature they go the contrary
way, and by their smallest species reach the confines of
those microscopic tribes that are at the bottom of the
gcale of animal life. I possess an undescribed beetle,
allied to Silpha minutissima E. B. % which, though fur-

" S. minutissima of Marsham is synonymous with Bcrmcstcs atc-
mariiis De Geer, Scaphidiim atomarium Gyllenh., and Lad idiiis fasci-
cularis Ilerbst., but surely arranging with none of these genera, being

DEFINITION OF THE TERM INSECT.

nished with elytra, wings, anteiincp, legs, and every other
oroan usually found in the order it belongs to, is abso-
lutely not bigger than the full stop that closes this period.
In several other coleopterous genera there are also very
minute species, as in Cryptophagus, Anisotoma, Agathidi-
iim, &c. I know no oiihopteraus insect that can be called
extremely minute, except that remarkable one found on
the Continent in the nests of ants, the Blatta Acervorum
of Panzer^, but now called, I believe, Mi/}'mecoj)hilus :
nor indeed any in the Hemiptera, Neuroptcn-a, and Di-
ptcra^ that approach the extreme limits of visibility : but
in the Lepidojitera, the pygmy Tinea occidtella is almost
invisible except m flight, being scarcely thicker than
a horse's hair, and proportionably short ; indeed, many
others of those lovely Lilliputians, the subcutaneous TzVie^e,
decorated with bands of gold and silver, and studded
with gems and pearls, that in larger species would dazzle
the beholder's eye, are in size not much more conspicu-
ous. In the Hymenopta-a order. Ichneumon Punctiim of
Dr. Shaw, which forms so striking a contrast to his giant
Phasina dilatatum, being placed together in the same
plate; and another that I possess, under the trivial name
of ySf/owos, would elude the searching eye of the ento-
mologist unless when moving upon glass. Lmne named
the tribe of parasites to which these belong, Minuti,
on account of their generally diminutive size. But
these Uttle minims, under the superintendence of Pro-
vidence, are amongst the greatest benefactors of the

sufficiently distinguished from them and every other insect by its
singular capillary wings. In my cabinet it stands under the name of
Trichoplcryx K.

Panz. Fn. Germ. Init. Ixii, 24. Comp. Hor. Entomolof'. Addenda

4.2

DEFIMTJON OF THE TERM INSECT.

human race, since they keep within due bounds tlie va-
rious destroyers of our produce.

The number of minute species of insects seems greatly
to exceed that of large ones, at least in Europe, of which
it may be asserted probably with truth, that two-thirds
are under a quarter of an inch in length, and one-third
not exceeding much a duodecimal of it. It might hold
good perhaps in Coleoptera, Hymenoptera^ Diptera, and
Aptera : but in Orthoptera, Hemiptera^ Ncuroptera, and
especially Lepidoptera, a large proportion would be found
to exceed three lines in length. Neither can it be af-
firmed of extra-European species, of those at least pre-
served in cabinets, amongst Avhich it is rare to find an
insect less than the fourth of an inch long. This, how-
ever, must probably be attributed to the inattention of
collectors, who neglect the more minute species.

Though size forms a pretty accurate distinction between
insects and the great bulk oi'vertebraie animals, it affords
less assistance in separating them from the invertebrate
classes, which are of every size, from the monstrous bulk
of some Cephalopoda (cutde-fish) and Mollusca (shell-
fish, &c.) to the invisible infusory animalcule : but ex-
ternal characters, abundantly sufficient for this purpose,
may be drawn from the general covering, substance, form,
parts, and organs of the body. As I shall enter into pretty
full details upon, this subject when I come to treat of the
external anatomy of insects, I shall here, therefore, only
give such a slight and general sketch of the distinctions
just mentioned, as will answer the end I have in view. I
must here repeat what I have before observed, and what it
is necessary that you should always bear in mind, namely,

I
1

DEFINITION OF THE TERM INSECT. 43 |

that at the hraits of classes aiid of every other natural j
group, the characters begin to change, those peculiar to ,
the one group beginning gradually to disappear, and !
those of the other to show themselves; so that it is ira- ;
possible ahnost to draw up a set of characters so precise \
as exactly in every respect to suit all the members of any ;
natural group.

Whichever way we turn our eyes on the objects of !
creation, above — below — adiwart, analogies meet us in i
every direction, and it appears clear, that the Book of
Natm-e is a Book of Symbols, in which one thing repre-
sents another in endless alternation. And not only does j
one animal, &c. symbohze another, but even between the ]
parts and organs of one set of animals there is often an !
analogy as to their situation and icse, when there is little 1
or no affinity as to their structure — or again, tlie analogy i
is in their situation, without affinity in either sti'ucture
or use. Thus certain parts in one tribe represent other ,
certain parts of another tribe, though as to their structure \
there is often a striking disagreement. Tliis is particu- J
larly observable between the vertebrate and invertebrate
animals. I shall therefore, in my remarks on the ge-
neral and particular structure of insects, contrast it in its
most important points with that of the first-mentioned
tribe.

The first thing that strikes us when we look at an
insect is its outside covering, or the case that incloses its
muscles and internal organs. If we examine it attentively,
we find that it is not like the skin of quadrupeds and
other Vertebrata, covering the whole external surface of
the body ; but that in the large majority it consists of
several pieces or joints, in this respect resembling the

44 DEFINITION OF THE TERM INSECT.

skeleton of the animals just named; and that even in those
in which the body appears to have no such segments, as
in many of the Mites {Acarm L.), they are to be fomid in
tlie limbs. This last circumstance, to have externally
jointed legs, is the peculiar and most general distinction by
which the Insecta of Linne, including the Crustacea, may
always be known from the other invertebrate animals
■ If we proceed further to examhie the substance of this
crust or covering, though varying m hardness, we shall
find it in most cases, if we exclude from our considera-
tion the shells of the Mollusca, &c., better calculated to
resist pressure than that of the majority of animals that
have no spine. In all the invertebrate tribes, indeed, the
muscles, there being no internal skeleton, are attached
to this skin or its processes, which of course is firmer
than the internal substance; but in insects it is very often
rigid and horny, and partially difficult to perforate, sel-
dom exhibiting that softness and flexibility which is found
in the cuticle of birds and most quadrupeds. From this
conformation it has been sometimes said, that insects
carry their bodies on the outside of their body, or have
an external skeleton. This idea, though not correct in
all respects, is strictly so in this— that it affords a general
point of support to the muscles, and the whole structure
is erected upon it, or rather I should say withm it. The
difference here between Insects and the Vertebrata seems
very wide; but some of the latter make an approach to-
wards it. I allude to the Chelonian Reptiles ( Testudo L.),
n The Annelida have, however, sometimes jointed organs, which
facilitate their progressive motion whether vermicular or undulatory ;
but they cannot be deemed legs, since they neither support the body
nor enable it to walk, &c. LatrciUe Anim. inveriebr. Artie. Ann.
dii Miis. 1831.

DEFINITION- OF THE TERIM INSECT. 45

in which the vertebral cokimn becomes external or merges
in the upper shell. The cijdostovious fishes also are not
very wide of insects as to their integument. But on this
subject I shall be more full hereafter.

The forms of insects are so infinitely diversified that
they almost distance our powers of conception : in this re-
spect they seem to exceed die fishes and other inhabitants
of the ocean, so that endless diversity may be regarded
as one of their distinctions. But on all their variations
of form the Creator has set iiis seal of symmetry ; so that,
if we meet with an animal in the lower orders in which
the parts are not symmetrical, we may conclude in general
that it is no insect.

But it is by their parts and organs that insects may be
most readily distinguished. In the vertebrate animals,
the body is usually considered as divided into head,
trunks and limbs, the akdomen forming no part of the
skeleton ; but in the insect tribes, besides the organs of
sense and motion, the body consists of three principal
parts — Head, Trunk, and Ahdojnen — the Jirsf, as was
before observed, bearing the principal organs of sense
and manducation the second most commonly those of
motion ; and the third those generation — the organs of
respiration being usually common to both trunk and ab-
domen. These three primary parts, — though in some in-
sects the head is not separated from the trunk by any
suture, as for instance in the Arachnida ; and in others,
head, trunk, and abdomen form only one piece, as in some
mites, — still exist in all, and in the great majority they are
separated by incisures more or less deeply marked : this
is particularly visible in the Hijmcnopiera and Diptera,
which, in this respect, are formed upon a common model;

DEFINITION OF THE TERM INSECT.

and in the rest, with the above exceptions, it may be
distinctly traced.

The head of insects is clearly analogous to that of
vertebrate animals, except in one respect, that they do
not breathe by it. It is the seat probably of the same
senses as seeing^ hearings smelling^ tasting— oxvd more pe-
culiarly perhaps of that of touch. The eyes of insects,
though allowed on all hands to be organs of sight, are
differently circumstanced in many particulars from those
of the animals last mentioned ; they are fixed, have nei-
ther iris nor pupil, are often compound, and are without
eyelids to cover them during sleep or repose ; there are
usually two compound ones composed of hexagonal
facets, but in some instances there are four ; and from
one to three simple in particular orders. The antenna
of msects in number and in situation correspond with the
ears of the animals we are comparing with them ; but
whether they convey the vibrations of sound has not
been ascertained : that they receive pulses of some kind
from the atmosphere I shall prove to you hereafter— so
that if insects do not hear with diem in one sense, they
may, by communicating information, and by aeroscopy, to
use Lehman's term, not directly in his sense % supply the
place of ears, which would render them properly ana-
logous to those organs. That in number^ these remark-
able organs are tactors is generally agreed, but this is not
their universal use. That insects smell has been often
proved; but the organ of this sense has not been ascer-
tained. What has improperly been called the clypeus,
or the part terminating the face above the upper lip
[lahrum), is in the situation of the nose of the Vei-tehrata^
" De Antcnnis Tiiscci. ii. 65.

DEFINITION OF THE TERM IXSECT. 47

and therefore so far analogous to it, and in some cases
even in form : I dierefore call it the nose. Whether this
part represents die nose by being furnished with what
answer the purpose of 7iostrilSy residing somewhere at
or above the suture dmt joins it to the upper lip, I cannot
positively affirm; but from the observations of M. P.
Huber, with regard to the hive-bee, it appears that at
least these insects have the organ of the sense in question
somewhere in the vicinity of the mouth, and above the
tongue^ : analogy, therefore, would lead us to look for
its site somewhere between the apex of the nose and the
upper lip ; and in some other cases, which I shall here-
after advert to, there is further reason for thinking that
it actually resides at the apex of the nose. The organ of
taste in insects, though some have advanced their palpi
to that honour, is doubtless in some part within the
mouth analogous in a degree to the tongue and palate of
the higher ammals. The organs of manducation, in
what may be deemed the most perfect desci'iption of
mouth, consist of an zipper lip closing the mouth above,
a pair of inandibles moving horizontally that close its
upper sides, and a lotioer lip with a pair of maxilla at-
tached to it, which close the mouth below and on the
under sides, both labium and maxillae being furnished
with jointed moveable organs peculiar to annulose pedate
animals, called palpi. In some tribes these organs as-
sume a difl'erent form, that they may serve for suction ;
but though in many cases some receive an increment at

* Nouv. Ohs. sur les AbeiUes, ii. 3/6 — . It appears from M. Huber's
experiment, that it was only when the hair-pencil, impregnated with
the oil of turpentine, was presented " pres de la cavite, au dessus
de I'imerfioH de la troupe" that the bee was sensible of the odour.

48 DEFINITION OF THE TERM JKSi;CT.

the expense of others, and a variation in form takes place,
none, as M. Savigny has elaborately proved, are totally
obliterated or without some representative'. The organs
now described, except the upper lip, are formed after
a quite different type from those of Vertehrata, with which
they agree only in their oral situation and use.

The second portion of the body is the Trunic, which
is interposed between the head and abdomen, and in
most insects consists of three principal segments, sub-
divided into several pieces, which I shall afterwards ex-
plain to you. I shall only observe, that some slight ana-
logy may perhaps be traced between these pieces and the
vertebrae and ribs of vertebrate animals, particularly the
Chelonian reptiles. This is most observable in Gri/Uus L.
and LibelMa L., in which the lateral pieces of the trunk
are parallel to each other''. In the Diptera and many
of the Aptera most of these pieces are not separated by
sutures. Each of the segments into which the trunk is
resolvable bears a pair of jointed legs, the first pair point-
ing to the head, and the two last to the anus. These legs
in their composition bear a considerable analogy to those
of quadrupeds, &c., consisting of hip, thigh, leg, and
foot ; but the last of these, the foot or Taj'sus, is almost
universally monodactyle, unless we regard the Calcaria
that arm the end of the tibia, as representing fingers or
toes, an idea which their use seems to justify. Achcta
monstrosa and Tridactylus paradoxus, however S exhibit
some appearance of a phalanx of these organs. They
differ from them first in number, the thoracic legs being

" Anim. sans Vertebr. I. i. Mem. i.
b Plate VIII. Fig. 10—14; IX. Fig. 6—8.
Coqucbert Ilhisl. Ic. iii. t. xxi./. 3.

DF.FINn'ION OF THE TERM IA\'i£CT.

4.9

invariably sisc in all insects, with the exception of the
Octopods or most of the Trackcan Arachnida^ which have
usually eight. In the Myriapods, though there are hun-
dreds of abdominal legs, only six are affixed to the trunk.
Next they differ with regard to the situation of their legs;
for though the anterior pair or arms are analogous in
that respect, the posterior pair are not, since in qiiadi-u-
peds these legs are placed behind the abdomen, but in
insects before it — in fact, in the former the legs may be
considered as placed at each end of the body, excluding
only the head and tail, but in the latter in the middle.
Though they correspond with those of quadrupeds in
being in pairs or opposite to each otlier, yet their direc-
tion with respect to the body is different, the legs of
quadrupeds, &c. being nearly straight, whereas in insects
they are bent or form an angle, often very obtuse at the
principal articulations, which occasions them to extend
far beyond the body, and when long to inclose a propor-
tionally greater space. The wi?igs are the organs of
motion with which the upper side of the trunk is fur-
nished ; and these, though they are the instruments of
flight, are in no other respect analogous to those of
birds, which replace the anterior legs of quadrupeds, lut
approach nearer, both in substance and situation, to the
fins of some fishes, and perhaps in some respects even to
the leaves of plants. M. Latreille is of opinion. That
the four wings or their representatives replace the four
thoracic legs of the decapod Crustacea''. Upon this
opmion, which shows great depth of research and prac-
tical acumen, I shall have occasion to express my senti-
ments when I come to treat more at large on the anatomy

" Hor. Entomolog. 413—.
VOL. III. £

50 DEFINITION OF THE TERM INSECT.

of the trunk and its members ; at any rate they do not
replace the two anterior pair of legs of the hexapod
Aptei-a. When merely used as wings, they commonly
consist of a fine transparent double membrane, strength-
ened by various longitudinal and transverse nervures, ot"
bones as some regard them, accompanied by air-vessels,
of which more hereafter, as well as of their kind and cha-
racters. I shall only observe, that insects are knowi
from all other winged animals, by having/our wings, or
what represent them, and this even generally in those
that are supposed to have only a pair. Another pecu-
liarity distinguishes the trimk of insects that you will
in vain look for in' the vertebrate animals — these are one
or two pair of lateral spiracles or breathing pores. Though
the respiratory sacs, &c. of birds are almost as widely
dispersed as the tracheae and bronchiae of insects*, yet
their respiration is perfectly pulmonary, and nothing like
these pores is to be discovered in them.

The principal pecuharity of the third part of the body,
the abdomen, is its situation behind the posterior pair of
thoracic legs, and its rank as forming a distinct portion
of what represents the skeleton. In most insects it is so
closely affixed to the posterior part of the trunk as to
appear like a continuation of it, but in the majority of
the Hymenoptera and Diptera^ and m the Araneidan
Arachnida, or spiders, it is separated by a deep incisure;
and in the first-mentioned tribe is mostly suspended to
the trunk by a footstalk, sometimes of wonderful length
and tenuity. In the Mammalia the male genital organs
are partly external; but in insects as well as in many of
the vertebrate animals, except when employed, they are
» N. Diet. d'Hist. Nat. xxviii.; compare 104 and 110.

DEFmiTION OF THE TERM INSECT.

retracted within the body. This part is the principal
seat of the respiratory pores or spiracles, many having
eight in each side, while others have only one.

Such are the principal external characters which di-
stinguish Insecta and Arachnida, or what we have here-
tofore regarded as insects, to which here may be added
another connected with their internal organization. The
imion of the sexes takes place in the same manner as
amongst larger animals ; and the females with vei-y few
exceptions, more apparent than real, are oviparous.
They are, however, distinguished by this remarkable pe-
cuharity already alluded to, that, except in the case of
the Arachnida^ one impregnation fertilizes all the eggs
they are destined to produce. In most cases, after these
are laid, the females die immediately, and the males after
they have performed their office, thougli they will some-
times unite themselves to more than one female. One
other circumstance may be named here — tliat no genuine
insect or Arachnidan has yet been found to inhabit the
ocean.

Before I conclude this letter, it is necessary to apprize
you, that every thing which it contains relative to the
characters of insects, has reference to them only in their
last or perfect state, not in those preparatory ones through
which you are aware that the majority of them must pass.
The peculiar characteristics of them in these states — in the
egg^ the larva, and the pupa, will be the subjects of my
next letters, which will be devoted to a more detailed
view of the metamorphosis of insects than I gave you
before when adverting to this subjects

» See above, Vor.. I. Ed. 4. p. 63—.
E 2

LETTER XXIX.

STATES OF INSECTS.

EGG STATE*

On a former occasion I gave you a general idea of what
has been called, perhaps not improperly, the metamor-
phosis of insects^; but since that time much novel and
interesting speculation on the subject has employed the
pens of many eminent Physiologists; and besides Uiis,
the doctrine then advanced of successive developments
has been altogether denied by a very able Anatomist,
Dr. Herold, who, with a hand, eye, and pencil, second
only to those of Lyonnet, has traced the changes that
gradually take place in the structure of the cabbage-but-
terfly {Pieris BrassiccB) on passing through its several
states of larva, pupa, and imag-o. It is necessary, there-
fore, that previously to considering separately and m

a The word usrccfcoP(poc^, and its derivative f^iTUfioq(pu<ris, are not
extant in any Greek writer before the date of the New Testament
They are used to express any external change of form or colour and
metaphorically an inward change and progressive improvement of tl>e
mind Comp. Matth. xvii. 2. ^lian. Var. Hist. 1. 1. c. 1. Rom. xm. 2.
2 Cor. iii. 18. They are, therefore, not improperly applied, as some
have supposed, to the changes of insects.

STATES OF INSECTS.

detail the states of insects, I should again call your atten-
tion to this subject, and endeavour to ascertain whether
Dr. Herold's hypothesis rests upon a solid foundation ;
or whether that adopted from Swammerdam by all tlie
most eminent Entomologists and Physiologists since his
time can be maintained against it.

I shall first give you a short abstract of the new hy-
pothesis.

According to Dr. Herold — The S2iccessive skins of the
cata'pillar, the pupa-case^ the future butterjiy, and its
parts and organs, excejJt those of sex lahich he discovered
in the newly excluded larva, do not preexist as germes, hut
are formed svx:cessively from the rete mucosum, which it-
self is formed anew upon every change of skin from what
he denominates the blood, or the chyle after it has p)assed
through the pores of the intestinal canal into the general
cavity of the body, where, being oxygenated by the air-
vessels, it performs the nutritive functions of blood. He
attributes these formations to a vis formatrix (Bildende
Kraft).

The caul or epiploon (Fett-rmasse), the corps graisseux
of Reaumur, S)-c., which he supposes to be formed, fom the
supeifuous blood, he allows, with most physiologists, to be
stored up iii the larva, that in the pupa state it may serve
for the development of the imago. But he differs from
them in assertiiig that in this state it is destitied to two
distinct purposes— first, for the prodiiction pf the muscles
of the butterfly, which he affirms are generated from it in
the shape of slender bundles of fibres ; — mid secondly, for
the development and nutrition of the mgans formed in the
larvq, to effect which, he says, it is dissolved again into
the mass (f blood, and being oxygenated by the air<-vessch.

5-4< STATES or INSECTS.

becomes Jit for nutrition, whence the epi})loon appears to
be a kind of concrete chyle^.

Need I repeat to you the hypothesis to which this
stands opposed— 7%flit every caterpillar at its first exclu-
sion contains within itself the germe of the future butterfly
and of all its envelopes, which successively j^resenting them-
selves are thrown of, till it appear in perfection and
beauty, with all its parts arid organs, when no further de-
velopment takes place.

I beheve you will agree with me, when you have read
and considered the above abstract of Dr. Herold's hy-
pothesis, that in it he substitutes a name for knowledge,
talks of a uw/oma/r/^ because his assisted eye cannot
penetrate to the primordial essence or state of the germes
of bemg, and denies the existence of what he cannot dis-
cover''. From ancient ages philosophers have done the
same, to conceal their own ignorance of causes under a
sounding name, when they have endeavoured to pene-
trate within the veil of the sanctum sanctorum, which it
is not permitted to vain man to enter. This has occa-
sioned the invention, not only of the term in question,
but of many others, as litde meriting the appellation of
Signs of ideas ; such as Plastic Nature, Epigenesis, Pan-
spermia, Idea seminalis, Nisusformativus, &c. But upon

a EntwickelungsgesMite der Schmetterlinge 13—27. 105—.

b Dr. Virey's observations under the article Emdrt/o (A. BtcL
d'Hut Nat. X. 195.) deserve here to be considered. " H y a done
nuelque chose au dessus de I'intelligence humaine dans cettc forma-
tion des etresj en vain on veut I'approfondir, c'est un abune dans
lequel on ne voit que la main de Dieu. A quoi bon s'appesantir sur
le mvstere de la formation des etres, sans esperance de 1 expliquer r'
Ne vaut-il pas mieux obsei-ver les op6rations de la nature autant
qu'il est perniis k I'ceil humain de les appercevoir ? "

STATES OF INSECTS.

this subject you cannot do better than consult what the
learned Dr. Barclay has said m his admirable work On
Life and 07-ganizatiofi\ in which he has placed th^
inanity, the vox et praterea nihil, of such high-sounding
terms in their true light The processes of nature in
the formation and development of the foetus in utero, of
the chick in the egg, of the butterfly in the caterpillar,
we in vain attempt fuUy to investigate ; yet we can easily
comprehend that pre-existent germes, by the constant
accretion of new matter in a proper state, may be gra-
dually developed, but we find it impossible to conceive
how, by the action of second causes, without the inter-
vention of the first cause, the butterfly should be formed
in the caterpillar, unless it preexists there as a germe or
foetus. " Is it not clear," asks Dr. Virey in his lively
manner, " as Blumenbach and other Physiologists main-
tain, that there is a formative power, a nisus formativus,
which organizes the embryo? Admirable discovery ! "
says he, " which teaches us that the foetus forms itself
because it forms itself ! As if you should affirm that the
stone falls because it falls" ! " Had Dr. Herold considered
what Bonnet says with as much good sense as modesty,
he would never have imagined that his discovering the
organs of the butterfly one after the other at certain pe-
riods in the caterpillar, was any sound argument agamst
their preexistence and coexistence as germes. " Or-
gans," says that amiable and excellent Physiologist,
" that have no existence as to us, exist as they respect
the embryo, and perform their essential functions ; the
term of their becoming visible is that which has been

» ^ xiv. " N. Diet. d'Hist. NaL x. 193.

STATES OF INSECTS.

eiToneously mistaken lor the period of their existence
This has been Dr. Herold's grand error ; he mistook the
commencement of the appearance of the organs of the
butterfly for that of their existence, and yet the early ap-
pearance of the sexual organs ought to have led him to
a conclusion the reverse of that which he has adopted.

Dr. Virey has observed with great truth — that " Every
being has a peculiar and unique nature, which would be
impossible if the body was composed of parts made at
several intervals, and without a uniform power that acts
by concert^:" and every Physiologist acquainted with,
the history of msects that undergo a complete metamor-
phosis will allow, that their developments and acquisition
of new parts and organs take place according to a law
which regulates the number, kind, and times of them,
differing in different species, and which has had an m-
variable operation, since the first creation, upon every
sound individual that has been produced into the world.

In consequence of this law, one species changes its
skin only four times, and another^^w or six ;— in some
C^ses the first skins shall be covered or bristled with
hairs or spines, and the last be naked and without arms ;
^that which forms the case of the pupae shall differ in
form and substance from the preceding skins, varying in
both respects in different species; and finally the butterfly
shall invariably follow, when no other change but the

» CEnv. V. ?79. " II n'est pas exact de dire que le coeur, la tetc, et
la raoelle epiniere, sont formes les premiers dans les foetus dcs ani-
ipaux a sang rouge et vertebres," says Dr. Virey; " mais il faut dire
seulement que tel est Tprdre dans lequel ces organes commencent a
devenir visiblcs." N. Did. d'Hist. Nat. x. 196.

" JOid. 193,

STATES OF INSECTS.

last mortal one shall take place. Can this law, so con-
stantly observed, be the result of a blind power? Or are
we to suppose that the Deity himself is always at work
to a-eate the necessary organs in their time and place ?
Is it not much more consonant to reason and the general
analogy of nature, to suppose that these parts and organs
exist in embryo in the newly-hatched catei-pillar, ami
grow and are successively developed by the action of the
nutritive fluid ? In the pupa of many Diidera the in-
closed animal, even under the microscope, appears with-
out parts or organs, like a mere pulp ; but Bonnet tells
us, that if boiled, all the parts of the pupa appear^, which
proves the preexistence of these parts even when not to
be discerned, and that nothing but the evaporation of
the fluids in which they swim is wanted to render them
visible.

Mr. William MacLeay has with great truth observed:
*' The true criterion of animal as well as vegetable per-
fection is the ability to continue the species ^ ;" and in
their progress to this state certain changes take place in
the parts and organs of all animals and vegetables :
there is, therefore, an analogy in this respect between
them ; and this analogy also furnishes another argument
against Dr. Herold's hypothesis, as we shall presently
see. These changes are of three kinds : In the vege-
table kingdom, at least in the phaenogamous classes, there
is a succession of developments terminating in the ap-
pearance of the generative organs, inclosed in the flower ;
in this kind the integuments, or most of them, are usually
persistent. In insects and other annulose and some ver-
tebrate animal??, there is a succession of spoliations, or

CEuvr. viii, 315. ^ Hvr. Eiiloinolog. 1-16.

STATES -OF INSECTS.

simultaneous changes of the whole integument, till the
animal appears in its perfect form with powers of repro-
duction ; in this kind the integuments are cadmous. — In
man and most of the vertebrate animals there is a gradual
action of die vital forces in different organs till they are
fitted for reproduction ; accompanied, as progess is made
to the adult state, by the acquisition of certain organs,
&c. as of teeth, horns, pubes, feathers, &c.=' Let us now
consider a little in detail the analogies that appear to exist
between the second and the first and third kinds. I shall
first consider the latter as the least obvious. That able,
judicious, and learned physiologist, Dr. Virey, has pointed
out no inconsiderable resemblance between the metamor-
phosis of the insect, and the changes, which he denomi-
nates a metamorphosis by metastasis, to which most ver-
tebrate animals are subject. In them, he observes, a state
analogous to the larva state begins at the exclusion of
the foetus from the womb ; it is deprived of teeth, and its
viscera are only accommodated to milk : in the cornute
species the horns are in embryo : the digestive system
now preponderates, and the great enjoyment is eating.
A second state, in a degree analogous to that o^ pupa,
commences at the period of dentition— the teeth now
produce another modification in the intestinal canal,
which becomes capable of receivmg and digesting solid
food : during this period the vital forces are all tending
to produce the perfect state of the animal; and in this
state, in man especially, the individual is educated and
fitted to discharge the duties of active life. Again, ana-
logous to the imago state is the age of puberty, in which

a See on this subject N. Did. d' Hist. Nat. xx. article Mciamo,-
phosis.

STATES OF INSECTS.

the complete development of the sexual powers takes
place in both sexes, and the animal has arrived at its
acme, and can continue its kind*: now the digestive
powers diminish in their activity, and love reigns para-
mount. When this state is fully attained, no further or
higher change is to be expected, and the progress is soon
towards decay and the termination of the animal's mortal
career. So we see that in fact man and other mammalia,
though they do not simultaneously cast their skins like
the insect ; or pass into a state of intermediate repose,
before they attain the perfection of their nature, hke the
caterpillar ; have their three states^ in each of which they
acquire new parts, powers, and appetites.

But a more striking analogy has been traced between
the insects that undergo a complete metamorphosis and
the vegetable kingdom ; for though the primary analogy
seems to be between the Polypus and the Plant, yet the
secondary one with the Insect is not by any means remote.
There are circumstances to which I shall have occasion
hereafter to call your attention, which afford some ground
for supposing, that the substance of the insect and the
vegetable partakes of the same nature, at least approxi-
mates more nearly, than that of the insect and the verte-
brate animal ; and every one who has observed these little
creatures with any attention, will have observed amongst
them forms and organs borrowed as it were from the
kingdom of Flora; and vice versa the Botanist, if he
makes the comparison, will find amongst his favourite
tribes many striking resemblances of certain insects.
But the analogy does not stop here ; for the butterfly
and the plant appear to have been created with a parti-

" /V. Diet. d'Hisl. Nat. xx. 349—.

GO STATES OF INSECTS.

cular reference to each other, both in the epoch of their
appearance and the changes that take place in them,
Tims, as Dr. Virey has observed, the caterpillar is si-
multaneous Avith the leaf of the tree or plant on which it
feeds, and the butterfly with the flowers of which it im-
bilges the nectar^. Swammerdam, I believe, was the first
who noticed the analogy between the changes of the insect
and the vegetable, and has given a table in which he has
contrasted their developments, mcluding otlier animals
that undergo a metamorphosis'': an idea which has been
generalized by Bonnets and adopted and enlarged by
Dr. Virey A state analogous to that of the larva in
the msect begins in the plant when it is disclosed from
the seed, or springs from its hybernaculum in the bulb,
&c., or is evolved from the gemma; integument after in-
tegument, often in various forms, as cotyledon, radical,
cauline, or floral leaves, expands as the stem rises, all
which envelopes incase the true representative of the
plant, the fructification, as the various skins do the future
butterfly. When these integuments are all expanded,
the fructification appears inclosed by the calyx or corolla
as the case may be, in which the generative organs are
matured for their oflice— this is the bud, which is clearly
analogous to Vhepupa state of the insect. Next the calyx
and corolla expand, the impregnation of the germen takes
place, and the seed being ripened, and dispersed by the
opening of the seed-vessel or ovary of the plant, the in-
dividual dies: thus the imago state of the insect has its
representative in the plant. " If we place," says Dr. Virey,
« here the egg of the insect, next its caterpillar, a little

» N. Did. d'Hisf. Xnl. XX. 348.

b mb/. NaL Ed. Hill. ii. 138. ^ O^"^"- -83" ,

STATES OF INSECTS.

farther the chrysalis, and lastly the butterfly — what is
this but an animal stem — an elongation perfectly similar
to-that of the plant issuing from the seed to attain its
blossoming and propagation ? *

There being, therefore, this general analogy in their
progress to that state in which they can continue their
species between every part of animated nature, it holds
good, 1 think, that the same analogy should take place
in their developments. If the adult man or quadruped,
i&c. is evidently an evolution of the fcetus, as from mi-
croscopical observations it appears that tliey are**, if the
teeth, horns, and other parts, &c. to be acquired in his
progress to that state are already in him in their embryos,
we may also conclude that the butterfly and its organs,
&c. are all in the newly-hatched caterpillar. Again, if the
blossom and its envelopes are contained in the gemma, the
bulb, &c. where they have been discovered it follows
analogically that the butterfly and its integuments all
preexist in its forerunner.

Perhaps after this view of the objections to Dr. He-
rold's hypothesis, it will not be necessary to say much
with regard to the argument he draws from the change
of organs — the loss of some and the acquisition of others
— since this may readily be conceived to be the natural
consequence of the vital forces tending more and more
to the formation of the butterfly, and the withdrawing
of their action more and more from the caterpillar ; I
shall not, Uierefore, enter further into the question, espe-

» iV. Diet. d'Hist. Nat. xx. 355.
Leeuwenhoek discovered in the incipient foetus of a sheep, not
larger than the eighth part of a pea, all the principal parts of the
future animal. Arc. Nat. I. ii. 165, 173.

" Bonnet, (Euvr. v. 284.

STATES OF INSECTS.

cially since the change of organs will come more regu-
larly under our notice upon a future occasion.

Winged insects, many branchiopod Crustacea^ and the
Batracian reptiles, have been observed by Dr. Virey to
bear some analogy to the mammalia^ aves, &c. in another
respect. In leavmg their egg, they only quit their first
integument, answering to the chorion or external envelope
of the human foetus; they therefore still continue a kind
of foetus, so to speak, more or less enveloped under other
tunics, and principally in their amnios, or the covering
in which the foetus floats in the liquor amnii^. This the
butterfly does in the pupa case ; and its birth from this,
under this view, will be the true birth of the animal. In
the hiunan subject, the ova upon impregnation are said
to pass from the ovary through the Fallopian tube into
the uterus. In die insect world, upon impregnation, the
eggs pass first from the ovaries into the oviduct, answer-
ing to the Fallopian tube, which in them terminates in
the ovipositor, or the instrument by which the parent
animal conveys the eggs to their proper station : there
is, therefore, nothing properly analogous to the uterus in
the insect, and the substance upon which the larva feeds
upon exclusion answers the purpose of a placenta.

After this general view of the most modern theories
with regard to the metamorphosis of insects, I shall in the
present and some following letters, treat separately of the
different states through which these little beings suc-
cessively pass.

The first of these is the Egg state, the whole class of
insects being strictly oviparous. Some few tribes indeed

" N. Diet. d'Hixt. Nat. xx. 352.

STATES OP INSECTS.

bring into the world living young ones, and have on that
account been considered as viviparotis, but incorrectly,
for the embryos of none of these are nourished, as in the
true viviparous animals, within a uterus by means of a
placenta, but receive dieir development within true eggs
which are hatched ui the body of the mother. This is
proved by the observations of Leeuwenhoek, who found
eggs in the abdomen of a female scorpion^ ; and of
Reaumur, with regard to the flesh-fly {Musca carnaria)
and other viviparous flies as they have been called''. A
similar mode of production takes place in vipers and
some other reptiles, which have hence been denominated
ovo-viviparous, to distinguish them from the true vivi-
parous animals — the class Mammalia. By far the larger
portion of insects is oviparous in the ordinary acceptation
of the term. The ovo-viviparous tribes at present known
are scorpions ; the flesh-fly and several other flies ; a
minute gnat belonging to Latreille's family of Tipularido
some species of Cocais ; some bugs ( Cimicida;)^ ; and most
Aphides, which last also exhibit the singular fact of indi-
viduals of the same species being some oviparous and
Others ovo-viviparous, the former being longer in propor-
tion than the latter. — Bonnet, however, is of opinion that
the eggs of the first are not perfect eggs, but a kind of
cocoon, which defends the larva, already formed in some
degree, from the cold of winter ^

Select Works by Hoole, i. 132. The fact is confirmed by M. L.
Dufour, who, having opened the abdomen of a female scorpion, found
in the midst of some eggs nearly mature a little scorpion a quarter
of an inch long ; it lay without motion, with its tail folded under the
body. N. Did. d'Hist. Nat. xxx. 426.

^ Reaum. iv. 425—. « Ibid. 428—. t. xxix./. 10, 11.

Busch, a German author, affirms that many Cimicidce are subject
to this law. Schneid. i. 206.
' Quoted in Huber Fourmis, 208. Some reptiles also are at one

64- STATES OF INSfeCI'S;

When excluded from the body of tlie mother, or from
the e<Tii-, as has been before observed, some insects appear
nearly in the form of their parents, which, with a very
slight alteration, they always retain; others, and the
greater number, assume an appearance totally different
from that of dieir parents, which they acquire only after
passing through various changes. It is to these last, which
have chiefly engaged the attention of Entomologists,
that the title of metamorphoses has been often restricted.
As, however, those insects which undergo the slightest
change of form, as spiders do, undergo sow^ change, and
almost all insects cast their skins several times before
they attain maturity, Linne and most Entomologists, till
very recendy, have regarded the whole class as under-
going metamorphoses, and as passing through /owr dif-
ferent states, viz. the Egg— the Larva— the Pupa— and
the Imago.

It is obvious, however, that in ovo-viviparous species
three states of their existence only come under our cog-
nizance, as these, being hatched in the body of the
mother, come forth first under the form of larva. There
is even one tribe of insects which presents the strange
anomaly of being born in the pupa state. This is the
Linnean genus Hippohosca {Pupipam fam. Latr.), to
which our forest-fly belongs, the females of which lay
bodies so much resembling eggs, that they were long
considered as such until their true nature was ascertamed
by Reaumur (most of whose observations were confirmed
by De Geer), who, from their size, which nearly equals
time oviparous, and at another ovo-viviparous. K Diet. cTHisU

'^'I't-L^ all insects, because the larv. H„tera^^
Dipleram-e supposed not to undergo this change. A. Dtct.dB.sL
Nal. XX. 363.

STATES OF INSECTS.

that of the parent fly — from their slight motion when
first extruded — from spiracnliform points which run down
each side of them — and lastly, from their producing not
a larva, as all other insects' eggs do, but perfect flies in
the winged state — inferred, and doubtless with reason,
that they are not real eggs, but pupae, or larvae just ready
to assume the pupa state, which, however strange it may
seem, have passed the egg and larva states in the body
of the mother

Insects, therefore, as to their mode of birth, may be
divided into —

I. Ovo-viviparoiis^ subdivided into —

1. Larviparoics, commg forth from the matrix of the

mother in the state of larvae, as the Scoipion
{Scm-pio), the Flesh-fly (Musca), the Plant-louse
(Aphis), &c.

2. Pupiparous, confinuing in the matrix of the mo-

ther during the larva state, and coming forth in
that of pupa, as the Forest-fly {Hippobosca
equina), the Sheep-louse (Melop/iagus ovinus),
the Bat-louse [Nycterihia Vespei-tilionis), &c.

II. Oviparous. All other insects.

Our business for the remamder of this letter will be
with the latter description of these little animals.

The unerring foresight with which the female deposits
her eggs in the precise place where the larvae, when ex-
cluded, are sure to find suitable food ; and the singular
instruments with which, for this purpose, the extremity
of their abdomen is furnished, have been noticed in a
former letter ^ and those last mentioned will be adverted
to in a future one. I shall now, therefore, confine myself

* Reaum. vi. Mem. xiv. De Geer, vi. 280.
See Vol, I. Lett. xi.
VOL. III. w

(jg STATKS OF INSECTS.

to Other circumstances connected with tlie subject, ar-
ranged for the salte of order under several distinct heads,
as— their exclusion— situation-substance— nwnber— size
_jlgare— colour— mi period of hatching.

i. Exclusion. The exclusion or extrusion of the im-
precated eggs takes place, when, passing from the ovary
Lo the oviduct, they are conducted by means of the
ovipositor, in which it terminates, to their proper situa-
tion By far the greater number of insects extrude them
singly, a longer interval elapsing between the passage of
eai egg in some than in others. In those tnbes which
place tteir eggs ii. groups, such as most butterflies and
moths, and many beetles, they pass from the ovaries
usually with great rapidity; while in the Ichnnmon.d^,
Sphegid^, (Estri, and other parasitic genera, which usu-
ally deposit their eggs singly, an interval of some nimutes,
hours, or perhaps even days, intervenes between th x-

trusion of each egg. One ^^-^V" P T.* So t

former mode I noticed in my letter on the Pe^fict Socte-
ties of Insects' ; another may be cited, to which you may
vourselfbeawitness_I allude to that common moth,
ZZy called the Ghost (Hepialus W which lay
l iar™ number of minute black eggs, resemblmg grains
o ;Xowder, and ejects them so fast that, accordmg o
De Geer, they may be said to run from tlie oviduc^ and
°e fom times expelled with the force of a popgun^ A
aresometim f^hjeh is uncertain, is

Tetrapterous msect, *e genus

■.A ,vhen it is taken, to discharge its eggs
: 1= And a friend of mine, who had obsen-ed wiUi a^
Q.g\xn . common crane-fly {Tipula),

tention the proceedmgs ot a common j .

TT -xa " De Geer i. 494—

a See Vol. II. p.. „i-,cprvpcl it near Lisieux m

c Called by M. l'Abb6 P-aux ^vl o ob^n ed ^ > ^^^^
Normandy, Mouche Balistc. Diet, d Hrst. JSat.

STATES or INSECTS. (J*/

assui'ecl me tliat several females wJiich he caught pro-
jected their eggs to the distance of more than ten inches.

A few Dijptei-a extrude them in a sort of chain or
necklace, each egg being connected by a glutinous mat-
ter with that which precedes and follows it. In a small
species of a genus alhed to Psychoda (a kind of midge),
which one season was abundant in a window of my house,
this necklace is composed of eggs joined by their sides,
not unlike those strung by children of the seeds of the
mallow ^ Otlier Tipulidce on the contrary extrude their
eggs joined end to end, so as to resemble a necklace of
oval beads. Beris clavipes and Sciura Thomce, two other
flies, produce a chain about an mch long, consisting of
oval eggs connected, in an oblique position, side by side ;
an arrangement very similar prevails in the ribband of
eggs which drop from some of the Epliemerce^.

These eggs, like those of the insects first, mentioned,
though connected, are expelled in succession ; but other
tribes, as the Lihelhdidce, vnth the exception of Agrion^
many EpJiemerce, TricJiopterous insects, &c. expel the
whole at once, as it were in a mass. In those first men-
tioned they are gummed together in an oblong cluster <=.
In one Ephemera mentioned by Reaumur'', they formed
two oblong masses, each containing from three to four
hundred eggs, and three and a half or four lines long.
These animals as soon as their wings are developed eject
these masses by two orifices, and are aided in the process
by two vesicles full of air, wherever they happen to alight
or to fall; in most instances it is the water, their proper
element, that receives them, but the animal does not ap-
pear to know the diiference between a solid and a liquid,

» Plate XX. Fig. 20. » Reaum. vi. .509. t. xLv.f. 11 12

" Reaura. vi. 434. <i /^/of. yi. 494. '

F 2

68 STATES OF INSECTS.

and seems only anxious how to free herself from a bur-
then that oppresses her; all has been contrived that an
insect so short-lived may finish her different operations
with the utmost celerity : the term of her existence would
not have admitted the leisurely extrusion of such a num-
ber of eggs in succession^ Some Trichoptera, or May-
flies, as''phiyga7iea grandis L., exclude their eggs in a
■ double packet, enveloped in a mass of jelly, (a circum-
stance often attending the eggs that produce aquatic
larvae,) upon the leaves of willows^ A similar double
packet m the year 1810 I observed appended to the anus
of a black species with long antennae, probably Phry-
ganea atrata F. ^ Upon taking several of the females I
was surprised to find in the above situation a seemmgly
fleshy substance of a dirty yellow. At first, from its an-
nular appearance, I conceived it to be some parasitic
larva, but was not a little surprised upon pullmg it away
that it was fuU of globular transparent dusky eggs:^it
was about two hues and a quarter in length and nearly
one in breadth. Being bent double it was attached to
the animal by the intermediate angle, and when un-
folded was constricted in the middle^. Each half, which
was roundish, had about ten sharp transverse ridges,
the mterstices of which appeared as if crenated, an ap-
pearance produced by the eggs which it contamed
Upon more than gentle pressure it burst and let out
the eggs. Though resembling the packet of P. grandn
in shape and other circumstances, it was nothmg like

. The vesicle, .hich Reau.ur f^^-:^;::^^^^^^
as well as assisting in the extrusion of the masses oi egg ,

figured <.xliv./, 10. ««.

b De Geer ii. 534. t. xm./. 13.

c Coquebert Illustr. Ic. t. If. A. B.

<« Plate XX. Fjo. 25.

STATES OV INSECTS.

jelly, but had rather a waxy appearance, and seems to
have been covered by a membrane : so that the ex-
cluded larvae must probably have eaten their way out
of it. I have still by me, in 1822, specimens of these
egg-packets, which, after the lapse of so many years, re-
tain their original form and colour. It is not improbable
that other species extrude their eggs in a similar case.
Scopoli says of P. hicaudata L., that the female carries
about under her belly her eggs united into a globe, like
Lycosa saccata^. The eggs of Geometra Potamogata F.
are also enveloped in a gelatinous substance, and the
mass is covered with leaves''.

Insects of the Diptera order also, like frogs and toads,
commit their eggs to the water imbedded in masses of
jelly. Dr. Derham describes two different kinds of
them, in one of which the eggs were laid in parallel rows
end to end, and in anoUier in a single row, in which the
sides were parallel <=. But the most remarkable and
beautiful specimen of this kind that I ever saw was one
that, many years ago, I took out of a pond at Wittersham
in Kent, from which I requested a young lady to make the
drawmg I send you'*. The mass of jelly, about an inch
and a quarter long, and rather widest in the middle, was
attached by one end to some aquatic grass, and from one
end to the other ran a spiral thread of very minute eggs,
the turns of the screw being alternately on each side.

The mode of exclusion of the eggs of the Blatta, which
are engaged for a whole week in the business of oviposi-
tion, is very singular : the female deposits one or two
large suboviform capsules, as large as half their abdomen,
rounded on one side, and on the other straight and ser-

» Eni. CarnioL 269. n. 705. ^ Reaum. ii. 401.

' In Rail Hisf. Ins. 264. J Plate XX. Fig. 24.

70 STATES OF INSECTb.

rated, which at first is white and soft, but soon becomes
brown and hard. This egg-case, as it may be called,
contains sixteen or eighteen eggs arranged in a double
series, and the cock-roaches when hatched make then-
escape through a cleft in its straight side, which shuts so
accurately when they have quitted it; that at first it ap-
pears as entire as before ^ The insects of the genus
Mantis also, or what are called praying insects, v^hen
they deposit their eggs, eject with them a soft substance,
which hardens in the air and forms a long kind of enve-
lope resembling parchment, in which the eggs are ar-
ranged also in a double series. And the Locusts {Gryl-
lus\ocusta L.) are said by Morier'' to deposit in the
ground an oblong substance, of the shape of their abdo-
men, which contains a considerable number of eggs ar-
ranged neatly in rows. The peristaltic motion observed
in the females of some insects during oviposition has been
before described

ii. Situation. Under this head I include the situation
in which the female insect places her eggs when extruded,
whether she continues her care of them and carries them
about till they hatch, or whether she entirely deserts
them, placing them either without a covering within
reach of their food, or enveloping them in hair or other-
wise protecting them from accident or the attack of ene-
mies. I shall consider them under two views : Jirst, as
depositing their eggs in groups, whether covered or naked ;
and secondly, as depositing them singly.

" Goeze Nahwf. xvii. 183—. t. iv.f. 16-19. Comp. .V. Diet.
d'HisL JVaLiu. 475. and xix. 239. De Geer iii. 533.
Second Journey through Persia, 100 — .
<■ See Vol. II. p. 30.

STATES OF INSECTS.

, 1. Those that deposit tlieir eggs in groups are first to
be considered. I shall begin with those that protect them
with some kind of covering.

I have already mentioned in a foniier letter* the
silken bag with which Lycosa saccata Latr., a kind of
spider, surrounds her eggs, and in which she constantly
carries them about with her, defending them to the last
extremity. Many other spiders, indeed nearly the whole
tribe, fabricate similar pouches, but of various sizes,
forms, texture, and colours. Some are scarcely so big
as a pea, others of the size of a large gooseberry ; some
globular, some bell-shaped ; others, the genus Thomism
Walck. in particular, depressed hke a lupine ; some of a
close texture Hke silk ; others of a looser fabric resem-
bhug wool : some consisting of a single pellicle, but most
of a double, of which the interior is finer and softer^;
some white ; others mclining to blue ; others again yel-
low or reddish; most of them are of a whole colour, but
that of Epeira fasciata is gray varied with black *=. And
while the parent spider of some kinds (the Lupi) always
carries her egg-bag attached to her anus, others hold
them by their palpi and maxillae ; and others suspend
them by a long thread, or simply fasten them in different
situations, either constantly remaining near them (the
Telarice\ or wholly deserting them (the Retiarice). The
eggs of one of these last Lister describes as often fixed
in a very singular situation — the cavity at the end of a
ripe cherry ; and thus, as he expresses it — " Stomachi
maxime delicatuli quoties hanc innocuam buccam non minus
ignoranter quam avide dexmrarunt^

Vol, I. p. 359—.
b Latr. HisL Nut. des Fourmis, .334. N. Did. d'Hist. Nat. ii. 284.
Lister De Aran. Tit. 13, 14. N. Diet. d'Hist. Nat. ii. 284.
Lister Ibid. 56. Tit. 15.

72 STATES OF INSECTS.

Herman informs us, that the species of the genus Che-
lifcr carry their eggs in a mass under their belly =».

Madam Merian gives an account of two species of
Blatta, which she affirms carry an egg-pouch about with
them— one species {B. gigantea?) she describes as car-
rying its eggs in a globular pouch of web like certain
spiders, and the other m a brown bag, which, when
alarmed, it drops and makes off ^. But this admirable
paintress of natural objects was not always correct in her
statements : it seems very improbable, from the habits
of those species of which we know the history, that any
of them should spin a pouch of web for their eggs.

The only insects certainly known to spin an egg-pouch
like the spiders, are the Hydrophili, a kind of water-
beetles. Some of these, as H. lividus, carry them about
with them, like Lycosa saccata, attached to the under
side of theii' body, as M. Miger observed ^ ; and others
when they are finished desert them. That of the great
water-beetle {Hydrophilus piceus) was long ago described
and figured by Lyonnet^ ; and a more detailed account
of it has since been given by M. Miger f. In form
it somewhat resembles a turnip when reversed, since it
consists of a pouch of the shape of an oblate spheroid,
the great diameter of which is three quarters of an inch ;
and the small, half an inch, from which rises a curved
horn, about an inch long and terminating in a pouit?.
The animal is fiirnished with a pair of anal spinners,
which move from right to left, and up and down, with

e N. Diet. d'Hisf. Nat. xxvi. 447- " Surinam, t.l

c A striking instance of this may be seen in her forty-nmth plate,
in which she has clapped the rostrated head of Fulgora laternana
upon the body of a Cicada Latr., affirming it to be the former fly m
its previous state ! This might be a trick upon her.

1 N. Diet. d'J-Iisf. Nat. XV. 489. - Lesser L. i. :300.

I .Amalesda Mmaun, xiv. 441. ' Lesser L. i. t. n./. xvi.

STATES OF INSECTS.

much quickness and agility : from these spinners a white
and glutinous fluid appears to issue, that forms the pouch,
which it takes the animal about three hours to construct.
The exterior tissue is produced by a kind of liquid and
glutinous paste, which by desiccation becomes a flexible
covering impermeable to water ; the second, which en-
velops the eggs, is a kind of light down of great white-
ness, that keeps them from mjuring each other. The
tissue of the horn is of a silky nature, porous and shinmg,
and greatly resembhng the cocoons of Lepidoptera. This
part, contrary to what Lyonnet supposes, appears calcu-
lated to admit the air, the water soon penetrating it when
submerged. At its base is the opening prepared for the
egress of the larvae, when hatched, which is closed by
some threads, that, by means of the air confined in the
cocoon or pouch, hinder the water from getting m».
This nidus does not float at liberty in the water till after
the eggs are hatched, the parent animal always attaching
it to some plant. By means of this anomalous process
for a beetle, which this insect is instructed by Providence
thus to perfect, the precious contents of its little ark are
secured from the action of the element which is to be the
theatre of their first state of existence, from the voracity
of fishes, or the more rapacious larvae of its own tribe,
until the included eggs are hatched, and emerge from
their curious cradle.

I shall next amuse you with a few instances, in which
the Allwise Creator instructs the parent insect, instead
of defending her eggs with a covering furnished by her
mternal organs, to provide it from without, either from

Miger Am. du Mus. ubi supr. Comp. N. Diet. d'Hist. Nat. xv.
482~.

74f STATES OF INSECTS.

her own body or from some other substance. Most
commonly, mdeed, the female leaves her cluster of eggs
without any other covering than the varnish with which
in this case they are usually besmeared. Either they are
deposited in summer and will soon be hatched, or they
are of a substance calculated to encounter and resist the
severities of the season. But many species, whose eggs
are more tender or have to resist the cold and wet of
winter, defend them in the most ingenious manner with
a clothing of different kinds of substance.

Cassida viridis, a tortoise beetle. Rose! tells us, covers
her group of eggs with a partially transparent membrane.
Arctia Salicis F., a moth, common on willows, wholly
conceals hers with a white frothy substance, which when
dry is partly friable and partly cottony, and being insoluble
in water effectually protects them from the weather*. The
female of Lophyrus Pini (a saw-fly), having by means
of her double saw made a suitable longitudinal incision
in the leaf of a fir, and placed in it her eggs in a single
row end to end, stops it up with a green frothy fluid
mixed with the small pieces of leaf detached by her saws,
which when dry becomes friable : a necessary precaution,
since these eggs are extremely brittle''. Arctia cliry-
sorh6Ea, Hypogymna dispar, and several other moths, sur-
round theirs with an equally impervious and more singular
clothing — hai?- stripped from their own bodies. Widi
this material, which they pluck by means of their pincer-
like ovipositor, they first form a soft couch on the sur-
face of some leaf : they then place upon it successively
layers of eggs, and surround them with a similar downy
coating, and when the whole number is deposited cover
» De Gcer i. 102. " Ibid. ii. 982.

STATES OF INSECTS.

the surface with a roof of hairs, which caimot be too
much admired; for those used for the interior of the
nest are placed without order, but those employed ex^
ternally are arranged with as much art and skill as the
tiles of a roof, and as effectually keep out the water, one
layer resting partly on the other, and all having the same
direction, so that the whole resembles a well-brushed
piece of shaggy cloth or fur. Wlien the motlier has
finished this labour, which often occupies her for twenty-
four hours, and sometimes even twice that period, her
body, which before was extremely hairy, is almost wholly
naked — she has stripped herself to supply clothing to her
offspring, and having performed this last duty she expires.
The female moths which thus protect their eggs are often
furnished with an exti'aordinary quantity of hair about the
anus for this express purpose ; and Reaumur conjectures,
that the singular anal patch of scales resembling those of
the wings, but considerably larger, which is found in the
female of Lasiocampa Pityocampa, is destined for the
same purpose^.

Reaumur had once brought to him a nidus of eggs
clothed still more curiously : they surrounded a twig in
a spiral direction, like those of Lasiocampa Neustria, but
were much more numerous, and were thickly covered with
fine down, not pressed close, but standing off horizon-
tally, which assumed much the same appearance as a
fox's tail would if twisted spirally round a branch"^.

A procedui'e nearly similar was observed by De Geer
in some species of Aphides {A. Alni and A. Primi), which
covered their eggs with a white cottony do^vu detached

= Reaiiin. ii, 97. 159.

^ Ibid. 107— . t. m.f. 15.

76 STATES OF INSECTS.

from their belly by means of their hind legs*. In this
case, however, the eggs were separately coated with the
down, but there was no general covermg to the group.

Several insects make the leaves and other parts of
plants serve as coverings for their eggs. Tenthredo
BoscB L., a saw-fly, and other species of the same genus,
with their saws make an incision in the green twigs of
shrubs and trees, and fill it with a line of eggs placed end
to end, taking care that, as the eggs grow after they are
laid, they are placed at such distances as to leave room
for their expansion''. Rhynchites Bacchus, a brilliant
weevil, well known to the vine-dressers for the injury it
doesS rolls with much art the leaves of the vine, so as to
form a cavity, in which it places its eggs ; other species
practise similar manoeuvres ; and some probably place
their young progeny in the interior of twigs, makmg an
openmg for that purpose with their rostrum— at least, I
once saw Rhynchites Alliarice L. with its rostrum plunged
up to the antennae in the twig of a crab-tree. Others of
this tribe, as we loiow, place their eggs in the mterior of
fruits and grain, as the nut, acorn, and common weevils.

It is probable that most of the above coverings serve
another purpose besides the protection of the eggs from
wet and cold— that of sheltering them from the action of
too great light, which, as Dr. Michellotti by numerous
experunents has ascertained, is fatal to the included
germe'i. On this account it is perhaps that so many in-
sects fasten their eggs to the under side of leaves. Those

» DeGeeriii.48.51. " Reaum. v. 12!

- See above. Vol. I. p. 196. 203.

■' Journ. de PIit/s. Philos. Mag. ix. 244.

STATES OF INSECTS.

exposed in full day have usually an opaque and horny
texture.

Some insects are spared all trouble in providing a
covering for their eggs, their own bodies furnishing one
in every respect adapted to this purpose. Not to mention
the Onisci, or wood-lice, since they rather belong to the
Crustacea, which have a four-valved cell imder the breast,
in which they carry their eggs, as the kangaroo does its
young in its abdominal pouch, the whole body of the fe-
male of those strange animals the Cocci becomes a cover-'
ing for her eggs, which it incloses on every side. To make
this intelligible to you, further explanation is necessary.
You must have noticed those singular immovable tortoise-
shaped insects, which are such pests to myi'tles and other
greenhouse plants. These are the young of a species of
Coccus (C. Hes_peridum L.), and their history is that of the
whole race. Part of them never become much bigger than
the size of which you ordmarUy see them, and when full-
grown disclose minute two-winged flies, which are the
males. The size of the females, which glue themselves to
a twig or leaf as if lifeless, now augments prodigiously,
and the whole body, distended with the thousands of eggs
which it includes to the bigness of a large pea, without
any vestige of head or limb, resembles a vegetable ex-
crescence or gall-apple rather than an insect. If you
remove one of them, you will perceive that the under
part of its abdomen is flat and closely applied to the
surface of the branch on which it rests, only a thin
layer of a sort of cotton being interposed between them.
In laying her eggs the female Coccus does not, like most
insects, protrude them beyond her body into day-light;
but as soon as the first egg has passed the orifice of her

' STATES OF INSECTS.

oviduct, she pushes it between her belly and the cottony
stratum just mentioned, and the succeeding eggs are de-
posited in the same manner until the whole are excluded.
You will ask how there can be found space between the
insect's belly and the cotton, to which at first it was close-
ly applied, for so large a mass of eggs ? To comprehend
this, you must consider that nearly the whole contents of
its abdomen were eggs ; that in proportion as these are
extruded a void space is left, which allows the skin of
the under side of the body to be pushed upwards, or
towards that of the back, affording room between it and
the cottony web for their convenient stowage. If you
examine the msect after its eggs are all laid, you will find
that they have merely changed their situation ; instead
of being on the upper side of the skm forming the belly,
and within the body, they now are placed between it
(now become concave and nearly touching the back) and
the layer of cotton. As soon as the female Coccus has
finished her singular operation she dies ; but her body,
retaining its shape, remains glued upon the eggs, to
which it forms an arched covering, effectually protecting
them, until they are hatched, from every external injury.
Some species lay so many eggs, that the abdomen is not
sufficiently large to cover the whole mass, but merely
one side of it, the remainder being enveloped in cottony
web*.

I am next to consider the situation of those eggs that
are excluded by the mother in groups mthout any other
covering than the varnish with which they are usually
besmeared in their passage from the oviduct. The fe-
" Reaum. iv. Mm. i.

STATES OF IJSISEC'I'S.

males only place them upon or near the food appropri-
ated to the young larvaa, to which they adhere by means
of the varnish just mentioned. These groups consist of
a greater or less number ; and when the eggs are hatched
by tlie heat of the sun, the larvae begin to disperse and
attack with voracity the food that surrounds them. It
is thus that most butterflies and moths attach their eggs
to the stems, twigs, and leaves of plants ; that the lady
birds {Coccinella), the aphidivorous flies {Syrphi^c.\ and
the lace- winged flies {Hemerohii\ deposit them in the
midst of plant-lice {Aphides); that the eggs of some flesh-
flies are gummed upon flesh ; tiiose of crickets and grass-
hoppers bm-ied in the earth ; those of gnats and other
Tipulidans set afloat upon, or submerged in, the water.

Frequently the whole number of eggs laid by one
female is placed in one large group, more commonly,
however, in several smaller ones, either at a distance
from each other on the same plant, or on distinct plants.
The object in the latter case seems to be, in some in-
stances, to avoid crowding too many guests at one table,
in others to protect the unhatched eggs from the voracity
of the larvae first excluded, which would often devour
them if in their immediate neighbourhood.

In the disposition of the eggs which compose these
groups much diversity prevails. Sometimes they are
placed without order in a confused mass : more fre-
quently, however, they are arranged in different, and
often in very beautiful modes. The common cabbage-
butterfly {Pieris Brassica) and many other insects place
theu's upon one end, side by side, so as, comparing
small things with great, to resemble a close column of
soldiers, in consequence of which those larvae which, on

80 STATES OF INSECTS.

hatching, proceed from the upper end, cannot disturb
the adjoining eggs. Many indeed have a conformation
purposely adapted to this position, as the hemisphaerical
eggs of the puss-moth {Cerura Vinula\ which have the
base by which they are gummed membranous and trans-
parent, while the rest is corneous and opaque. The
same ready exit to the larva is provided for in the oblong
eggs of the emperor moth [Saturnia Pavo?iia), which
are piled on their sides in two or more lines like bottles
of wine in a bin*.

Where the larva does not emerge exactly from the
end of the egg other arrangements take place. The
whirlwig-beetle {Gyrinus natator) and the saw-fly of the
gooseberry &c. {Tenthredo fava L.) dispose theirs end
to end in several rows ; the former upon the leaf of some
aquatic grass, the rows being parallel, the latter gununed
to the mam nerves of gooseberry or currant leaves, the
direction of which they follow

But the lackey-moths {Lasiocampa Neustria, castren-
sis, &c.) adopt a different procedure. As their eggs,
which are laid m the autumn, are not to be hatched until
the spring, the female does not, hke most other moths,
place them upon a leaf, with which they might be blown
by the winter's storms far from their destined food, but
upon the twig of some tree, round which she ranges them
in numerous cycles. If you examine your fruit-trees,
you can scarcely fail to find upon the young twigs col-
lections of these eggs, which are disposed with such ad-
mirable art, that you would take them rather for pearls,
set by the skilful hand of a jeweller, than for the eggs of

" Rosel, ix. 157. t. 2G5 ? " Ibid. iii. 197.

See above, Vol. I. p. 19.5.

STATES OF INSECTS.

an insect. Each of these bi'acelets, as the French gar-
deners aptly caU them, is composed of from 200 to 300
pyramidal eggs with flattened tops*, having their axes
perpendicular to the circumference of the twig to which
they are fastened, surrounding it in a series of from fif-
teen to seventeen close spiral circles, and having their
interstices filled up with a tenacious brown gum, which,
while it secures them alike from the wintry blast and the
attack of voracious insects, serves as a foil to the white
enamel of the eggs that it encompasses. It is not easy
to conceive how these moths contrive to accomplish so
accurately with their tail and hind feet an arrangement
which would require nicety from the hands of an artist ;
nor could Reaumur, with all his efforts and by any con-
trivance, satisfy himself upon this head. He bred num-
bers of the fly from the egg, and supplied the females
after impregnation with appropriate twigs ; but these, as
though resolved that imprisonment should not force from
them the secret of their art, laid their eggs at random,
and made no attempt to place them syntmetrically''.

This illustrious Entomologist was more successful in
discovering the mode in which another insect, the com-
mon gnat, whose group of eggs is, in some respects, as
extraordinary as that last described, performs its opera-
tions. The eggs of this insect, of a long phial-like form,
are glued together, side by side, to the number of from
250 to 300, into an oblong mass, pointed and more
elevated at each end, so as considerably to resemble a
little boat in shape. You must not here suppose that 1
use the term boat by way of illustration merely ; for it
has all the essential properties of a boat. In shape it

» Plate XX. Fig. 14. i> Reaum. i 95— /. 1—13.

VOL. III. Cr

^2 STATES OF INSECTS.

pretty accurately resembles a London wherry, being
sharp and higher, to use a nautical phrase, fore and aft;
convex below and concave above; floating, moreover,
constantly on the keel or convex part. But this is not
all. It is besides a life-hoat, more buoyant than even
Mr. Greathead's : the most violent agitation of the water
cannot sink it; and what is more extraordinary, and a
property still a desideratum in our life-boats, though
hollow it never becomes filled with water, even though
exposed to the torrents that often accompany a thunder-
storm. To put this to the test, I yesterday (July 25, liJH)
placed half a dozen of these boats upon the surface of a
tumbler half full of water ; I then poured upon them a
stream of that element from the mouth of a quart bottle
held a foot above them. Yet after this treatment, which
was so rough as actually to project one out of the glass
I found them floating as before upon their bottoms, and
not a drop of water within their cavity.

This boat, which floats upon the surface of the water
until the larvae are disclosed, is placed there by the female
gnat. But how? Her eggs, as. in other msects, are
extruded one by one. They are so small at the base m
proportion to their length that it would be difficult to
make them stand smgly upright on a sohd surface, much
more on the ^Vater. How then does the gnat contrive
to support the first egg perpendicularly until she has
glued another to it-these two until she has fixed a
third, and so on until a sufficient number is fastened to-
eether to form a base capable of sustaining them m
Lir perpendicular position ? This is her process She
fixes her four anterior legs upon a piece of leaf, or a
blade of grass, and projects her tail over the water. She

STATES OF INSECTS. 83

then crosses her two hind legs, and m the inner angle
which they form, retains and supports the first laid egg,
as it proceeds fi'om the anus. In like manner she also
supports the second, third, &c., all of which adhere to
each other by means of their glutinous coating, until she
feels that a sufficient number are united to give a stable
base to her little bark ; she then uncrosses her legs, and
merely employs them to retain the mass until it is of the
required size and shape, when she flies away, and leaves
it to its fate floating upon the water*.

It may not be out of place to mention here a re-
markable circmnstance which not seldom attends a kind
of water-scorpion {Naucoris F.) occasionally to be met
with in collections of Chinese insects. Its back is often
covered with a group of rather large eggs, closely ar-
ranged ; but whether these are its own eggs or those of
some large species of water-mite [Hydrachna Maill.) has
not been clearly ascertained. On the former supposition,
the ovipositor must be remarkably long and flexile to
enable the animal to place the eggs on its back. In con-
firmation of the latter it may be observed, that the spe-
cies of the genus Hydrachna usually attach their eggs
to the body and legs of aquatic insects, as for instance
H. abstergens to the water-scorpion {Nepa cmerea), 8lc.^

2. After having thus laid before you some of the pro-
cedures of those insects that usually deposit their eggs
in groups, either naked or defended by coverings of va-
rious kinds, I next proceed to a rapid survey of those of
the species that commonly deposit them singly. Some

Reaum. iv. 615—. t. xlvv.f. 2 — 7-

y. Dici.d'Hisl. Nat. xv. 445. Ros. iii. 156.

84 STATES OF INSECTS.

of these, as for instance the Admiral Butterfly {Vanessa
Atalanta), glue each egg carefully to its destined leaf by
alighting on it for a moment. Another butterfly {Hip-
parchia HyperantJms) 'whose caterpillar is polyphagous,
drops hers at random on different plants. In general it
may be observed, that all those larv£E which live in so-
litude, as in the interior of wood, leaves, fruits, gram,
animals, &c., proceed from eggs laid singly by the female,
which is usually provided with an appropriate instrument
for depositing them in their proper situation. Thus the
nut- weevil {Balaninus Nucim Germ.) and also that of the
acorn {B. Glandium) pierce a nut or an acorn with their
long beak, and then deposit in the hole an egg, from
which proceeds the maggot that destroys those fruits.
Leeuwenhoeck asserts that the common weevil {Calaii-
dra granaria) adopts the same process, boring a hole in
every single grain of corn before it commits an egg to it,
and at the same time, by this manoeuvre, prepares a small
quantity of flour to serve for the food of the tender grub
when it is first hatched ^ It is probable that tlie Rhyn-
cophorous or weevil tribe m general chiefly use their beaks
for the purpose of depositing their eggs in different vege-
table substances, and perhaps prmcipally m fruit or gram.
The tribe of gall-flies {Cynips) on the contrary, whose
economy, detaUed m a former letter^ interested you so
much, bore an opening for the egg with their sphal ovi-
duct, which also conveys it.

Another large tribe of insects depositing theu' eggs
singly, are tlrose which feed upon the bodies of other
animals, into the flesh of which they are either mserted,
or placed so as speedily to find their way into it. Some
*Epist.mi. u Vol.. I. p. 448-.

STATES OF INSECTS.

of these introduce them into living animals, and then
leave them to their fate, as the Ichneumons and gad-flies:
others deposit them along widi the dead body of an in-
sect interred in a hole, often prepared with great labour,
as the different species of sand-wasps {Sphecida:\ spider-
wasps [Pcmpilidcc), &c. : the manners of the latter of these
tribes have been already adverted to% and those of the
Ichneiimonida; will come more fully under consideration
when I treat of the diseases of insects.

A similar labour in providing suitable habitations for
their eggs is undergone by various otiier insects whose
larvae live chiefly on vegetable food, some inserting their
eo-o- within the substance the larva devours, as those that
prey on timber, twigs, roots, or the like, and others on
its surface. One would suppose at first, that the exceed-
ingly small egg which produces the subcutaneous larvjE
would, by the parent moth, be imbedded in the substance
of the leaf which is to exhibit hereafter their serpentine
galleries : but tliis is not the case, for she merely glues it
on the outside ; at least such was the situation of the only
egg of these very minute moths Reaumur had ever an
opportunity to observe''.

Other insects, belonging to the tribe which lay their
eggs singly, bury them in the ground. Of this descrip-
tion are many of the lamellicorn insects, the dung-chafers
{Scarabceidce MacLeay) particularly, which, inclosing
their eggs in a pellet of dung, deposit them in deep cy-
lindrical cavities. Concernmg the proceedings of some
of these, as well as of the whole race of bees, wasps, &c.,
which all lay single eggs, I have before detailed to you

» See above, Vol. I. p. 344—. " Reaum. iii. 8—.

STATES OF INSECTS.

many interesting particulars ^ I must not conclude this
subject without observing, that the female Pycnogonidce,
an osculant tribe between Insects and Crustacea^ carry
their eggs upon two pair of false legs

' iii. Substance. From this long dissertation on the sitU'
ation of the eggs of insects and matters connected with it,
I pass on to their substance or their external and internal
composition, giving at the same time some account of the
embryo included in them. The eggs of insects, like those
of birds, consist in the first place of an external coat or
shell, varying greatly, as to substance, in different genera.
Most commonly, particularly in those which deposit their
eggs in moist situations, as in dung, earth, and the like,
it is a mere membrane, often thin and transparent, and
showing, as in spiders, all the changes that take place in
the inclosed embryo, as the formation of the head, trmik,
and limbs This membrane is sometimes so dehcate
as to yield to the slightest pressure, and msufficient to
protect the included fluids from too rapid an evaporation,
if the eggs be exposed to the full action of the atmosphere.
In most Lepidoptera, and several other tribes, this mte-
gumentis considerably stronger, in those moths whose
eggs are exposed throughout the winter, as Lasiocampa
Neustria, &c., so hard as not to yield easily to the knife.
Even m these, however, its substance is more analogous
to horn or a stiff membrane than to the shell of the eggs
of birds. Nothing calcareous enters into its composition,
and it is not perceptibly acted upon by diluted sulphuric

* Vol. I. 349—. 371—. ^ ^. Diet. d'Hht. Nat. xxviii. 271-

* De Geer vii. 194.

\m\. i Wave ^sttfnm<i s*^enr»* </f tW. fA iri3*«*»,
fmvfi /lifWyjV*/ /»/>t>«r.^( of fW. ift t^^w-

I will nM, )>//wetCT, ««»rm 0»i*t H <U^a i^*A, <rA\^^ ihtm^t

tw:w\fTMf. that that ^/f '^rfvyfA.

W»thi/» th'w titif.p^mfietft >» 'tm\tu\fA\ n il»<'>y ' ■ ''^^

whitish /I Mid, /^.'W nr lut ( /inter viUiorm h*vfc ^>e«ri <r»fli^ <>r
indefid »re |/rjM;t/c«Me; Irfit it » fejM/>y»?«b{« to ^try^Af.^
that like tlie white mtd yf^k <A tl»fj t/wrf* ^
hr tlif; (hrv*;h/fmre»it (/f t»i*j r/r^»n* ^>f t)i« g«m»« <>f tl»«
Tutfire ifiaecU

Vfut firw ot«€rvaii«fw fnre rew^tkd flM* t** <^

enihryo iuMni in the eg«. It k »tete<l, tW rt »
veftt«l with an trxUetnely fine and fJelkato fMDkfe inp

jK^^l l/y fujine aiiah^mjft t</ tU Chf/rUm an*! /f/wni/y* of
the hiunan f(>ct«3, th</uj<h f/th^» t)m»k t>»e nkttXi <A the
«^ U> w/rre»fx>Ti(] with the O/rv/n^ vnA the mcMiWire
'uitt'.f(iiifi(mtfi </ ll»« lanra wit^i t}*#; Amnufi*. When the
ef^f^ i» first laid, nr/f.hing irwJ<;**l i«f t/^ ^i^i it hat the
fluid jij»t mfSJttUmcAl ; t}ic /»r»t chuuf^e ut t}rt» fhad » the
apfxjfirance r/f the fi^l </f the tifh\fryo, nu/re partieidiaAf
ill Colf;r///lf;ra, r/f two pr/intA, tfie nuVmiertU (A the mandn-
blc», and of tfir^sw; H^xinurtA hiUf the tratJi«c whid^i I
have callwl »j>iracle?> ; tie; little animal we rnay %r/pjj^^

» (;oroparc A^. rf*//**/. ^at, xr\. ^i. with xx. 33(2— > bo* »
the /fr/ini//« imrrte/Jiately f^'mre^/jn tfie fi«t*», the p«nicl«
anaK;j?f/ii» to it, and the ^hcll to Ch/rnfm.

J^amrri. //i///, Sal. cd. Hill J. 1253. a. Co«p. tf. Diet. 4^ Hid.
Nal. xv'i. 24C>.

STATES OF INSECTS.

then assumes its form and limbs. The embryo is usually
so folded in the egg that the head and tail meet*, and
the head, annuli, and other parts of the larva are often
visible through the shelP. Swammerdam even saw the
pulsation of the great dorsal vessel through the shell of
the egg of Oryctes ?iasicornis.

Under this head I must notice another singular cir-
cumstance peculiar I believe to the eggs of insects, that
sometimes, though rarely, they are covered with dovm or
hair. Those of a singular little hemipterous insect, of a
genus I believe at present undescribed, the ravages of
which upon the larch have been before noticed ^, are co-
vered by a downy web, as is the case with the animal
itself. De Geer has described the eggs of a bug, not
uncommon in this country {Pentatoma jwiiperina Latr.),
which are reticulated with black veins, in which very
short bristles are planted''. I possess also a nest of
brown eggs, probably of a species of the same genus,
found upon furze, which appear to be covered ^ith very
short downy hairs. The top of these is flat, and sur-
rounded by a coronet of short bristles, each surmounted
by a small white ball, so as to wear the appearance of a
beautiful httle Miicor. But hairy eggs are not confined
to the Hemiptera Order, for, according to Sepp, those of
the fiigure-of-eight moth {Bomhyx cceruleocephala) are of
this description^.

iv. Number. The fertility of insects far exceeds that of

Swamm. Ibid. ^ Sepp. iv. t. iii./. i. c. v. t. iv./. 2.

<= See above, Vol. I. p. 208: it is there called an Aphis, but it is a
distinct genus.

0 De Geer iii. 245. t. xiii./. 20—22.
« Sepp. iv. t. xiii./. 2. 3.

STATES OF INSECTS. 89

birds, and is surpassed only by that of fishes*. But the
number of eggs laid by different species, sometimes even
of the same natural family, is extremely various. Thus
the pupiparous insects may be regarded as producing
only a single egg ; Musca Meridiana L., a common fly,
lays two^ other flies six or eight; the flea twelve; the
burying beetle (NecropJionis Vespillo") thirty; May-flies
{Trichoptera K.) under a hundred; the silk-worm moth
about 500; the great goat-moth (Co5SM5Z2g7iz>^r6?a) 1,000;
Acancs ama-icanus more than 1 ,000 ^ ; the tiger-moth ( Cal-
limorpha Caja) 1,600; some Cocci 2,000, others 4,000;
the female wasp at least 30,000^; the queen bee varies
considerably in the number of eggs that she produces in
one season, in some cases it may amount to 40,000 or
50,000 or more •"; a small hemipterous insect, resembUng
a Uttle moth {Aleyrodes proletella Latr.) 200,000. But
all these are left far behind by one of the white ants
[Termes fatale F. hellicosus Smeath.) — the female of this
insect, as was before observed s, exti'uding from her enor-
mous matrix not less than 60 eggs in a minute, which
gives 3,600 in an horn*, 86,400 in a day, 2,419,200 in a
lunar month, and the enormous number of 211,449,600
in a year : probably she does not always continue laying
at this rate; but if the sum be set as low as possible, it
will exceed that produced by any other known animal in
the creation.

V. Size. The size of the eggs is in proportion to that of

» The sturgeon is said to lay 1,500,000 eggs, and the cod-fish
9,000,000.

" Reaum. iv. 392. « See above. Vol. 1. p. 350.

De Geer vii. 159. " See above. Vol. II. p. 109.

f Ibid. 159. 166. % Ibid. 3C— ,

90 STATES OF INSECTS.

the insect producing them, though in some instances
small ones produce larger eggs than those laid by bigger
species. Thus the eggs of many Aptera, as those of that
singular mite Uropoda vegetans, and of the bird-louse
found in the golden pheasant, are nearly as large, it is
probable, as the parent insect; while those of the ghost-
moth {Hepialus Humuli) and many other Lepidoptera,
&c. are vastly smaller. This circumstance perhaps de-
pends principally on the number they produce : the ma-
jority of them, however, are smaU. The largest egg
known, if it be not rather an egg-case, is that of a spectre
insect {Phasma dilatatum), figured in the Lmnean Trans-
actions \ being five lines in length and three in width,
which probably approaches near the size of tliat of some
humming-birds. The largest egg of any British insect
I ever saw was that of the common black rove-beetle
{Staphylinus olens) sent me by Mr. Sheppard— this is a
line and half long by a line in width. But we do not often
meet with msect-eggs exceeding a Ime in length. A vast
number are much smaller : those of Ephemerae are more
minute than the smaUest grains of sand^ and some almost
imperceptible, as those of the subcutaneous moths, to the
naked eye. Commonly the eggs laid by one female are
all of the same size; but in several tribes, those con-
taining the germe of the female are larger than those that
are to give birth to a inale. This appears to be the case
with those of the Rhinoceros beetle {Ori/ctes nasicornis^\
and according to Gould with those of ants^. As the
female in a vast number of instances is much bigger than
the male, it is not improbable that this law may hold

- iv.^.xviii./.4.5. De Geer ii. 638.

- Bibl. Ned. i. 132. b. " Gould 36.

STATES or INSECTS.

very extensively. It is stated, however, by Reaumur %
that the reverse of this takes place in the eggs of the
hive-bee, those that are to produce males being larger
than the rest.

Another pecuharity connected with the present head is
the augmentation in bulk which takes place, after exclusion,
in the esss of the great tribe of saw-flies ( Tenthredo L.), the
gall-flies {Cynips L.), the ants {Formica L.) and the water-
mites {Hydrachna Maill. Atax F.). Those of the two for-
mer, which are usually deposited in theparenchymous sub-
stance of the leaves, or of the young twigs, of various plants,
imbibe nutriment in some unknovni manner, through their
membranous skins, from the vegetable juices which sur-
round them^, and when they have attained their full size
are neai'ly twice as large as when first laid. Except in the
eggs of fishes, whose volume in hke manner is said to
augment previously to the extrusion of the yomig, there
is nothing analogous to this smgular fact in any other of
the OAT,parous tribes of animals, the eggs of which have
always attained theu' fiill size when they are laid.

It is to M. P. Huber that we are indebted for the
knowledge of the fact that the eggs of ants grow after
being laid, a circumstance favoured probably by the
moist situation in which the workers are always careful
to keep them. By an accurate admeasurement he found
that those nearly ready to be hatched were almost twice
as big as those just laid'=. A similar observation was
made on the red eggs of a water-mite [Hydrachna abs-
tergens) by Riisel, who conjectured that they draw their
means of increase from the body of the water-scorpions

" Rcivuni. V. 477. Ibid. iii. 579. v. 121. " Fourmis, 69— .

92 STATES OF INSECTS.

{Nejjce), of which they form so singular an appendage',
which opinion is confirmed by De Geer, who observes
that when the water-scorpions are covered by an unusual
number of the eggs of the water-mites, they grow weak
and languid, and endeavour to rid themselves of their
parasitic appendages''. It is most probable that the mite
lately named ( Uropoda vegetans), which is often found
planted as it were upon the bodies of various beetles, by
means of a long pedicle, through which, as the foetus by
an umbilical chord and placenta, it derives its nutriment
from the above animals, is at first so fixed in the egg
state, though before it is disengaged from the pedicle it
is hatched, since it is often found with its legs displayed
and quite active — this is the more probable, as the eggs
of the water-mite are fixed by a pedicle to the animals to
which they are attached I have met with a remarkable
instance, in which pedunculated eggs seem to draw nu-
triment fi-om the 7nother, which brings the pedicle still
near to the nature of the vunbilical chord. Those of the
small hemipterous insect which infests the larch before
alluded to, are attached to the anal end of the mother by
a short foot-stalk not longer than the egg.

Dr. Derham seems to have observed, that the eggs of
some Diptera, of the tribe of TipuUdcs, also increase in
size before the larva is excluded''. It seems to me likely
enough, that in this and many of the above cases in which
the egg is supposed to grow, it is rather an extension of
the flexile membrane that forms their exterior propor-
tioned to the growth of the included embryo fi'om food
a Rosel iii. 152. " De Geer vii. 145.

« Ibid. 123—. See above, Vol. I. p. 393.
0 Rmi Hist. Ins. 265.

STATES OF INSECTS.

it finds within the egg, than from any absorption from
without.

vi. Shape. We are accustomed to see the eggs of dif-
ferent species of oviparous anunals so nearly resembling
each other in form, that the very term egg-shaped has been
appropriated to a particular figure. Amongst those of
birds, with which we are most familiar, the sole variations
are shades of difference between a globular and oval or
ovate fiffure. The e^Bs of insects, however, are confined
by no such limited model. They differ often as much,
both as to their shape, sculpture, and appendages, as one
seed does fi'om another ; and it is not improbable that,
if duly studied, they would furnish as good indications
of generic distinctions as Gaertner has discovered in
those of plants, Theii- most usual form indeed is glo-
bular, oval, or oblong, with various intermediate modifi-
cations. We meet with them ovate, or of the shape of
the common hen's egg, flat and orbicular, elliptical, co-
nical, cylindi-ical, hemispherical, lenticular, pyramidal,
square, turban-shaped, pear-shaped, melon-shaped, boat-
shaped, of the shape of an ale-stand, of a drum, &c. ^,
and sometimes of shapes so strange and peculiar, that
we can scarcely credit their claim to the name of eggs.
Thus the eggs of the gnat are oblong and narrow, or
nearly cyUndrical, having at the top a cylindrical knob'',
so as to give them the precise form of the I'ound-bottomed
phial sometimes used by chemists : those of the common

Eggs of various shapes ai-e given Plate XX. Fig. 3 — 23. See also
Brunnich. Entomologia 4. iV. Diet. d'Hist. Nat. xvi. 245. Reaum. ii.
/. iii. iv. xiv. xxvi. xxvii. &c.
" Plate XX. Fig. 18.

94»

STATES OF INSECTS,

water-scorpion {Nepa cinerea) are oblong, and at the
upper end are surrounded by a sort of coronet, consisting
of seven slender rays or bristles of the length of the egg%
so as to resemble somewhat the seeds of Carduus hene-
dictus {Cnicus acarna^) of the old botanists. One would
think this spinous circlet a very awkward appendage to
bodies which are to be gradually extruded through the
fine membranous ovaries and oviduct which inclose them :
but they are so admirably packed, the unarmed end of
each egg fitting closely mto the space uaclosed by the
spines of the one next below it, or, rather, the spines
which are moveable, embracing it closely, that not only
is no room lost, but the ovaries are perfectly secure from
injury. The eggs of another species of this tribe {Ra-
natra linearis) have only two of these spines or bristles
—they are inserted in the stem of a water-rush {Scirpus)
or other aquatic plant, so as to be quite concealed, and
are only to be detected by the two bristles which stand
out from it ^ The eggs of the beautiful lace-wmged flies
(Hemerobius), those golden-eyed insects so serviceable m
destroying the plant-lice (Aphides^), are still more sin-
gular. Those of H". Perla are oval, and each of them
attached to a fihform pedicle not thicker than a hair,
and seven or eight times as long as the egg. By this pe-
dicle (which is supposed to be formed by a glutinous
matter attached to one end, which the female draws out
by abstracting her ovipositor with the egg partly in it

a Plate XX. Fig. 23. Swaram. Bibl. Kat. t. iii. /. 7, 8. In a
specimen I opened of this insect the bristles converged so as to form
a kind of tail to the egg.

b Darwin Phytolog. 512.

c Gcoffr. Ins. Par. i. 480. t. x./. \.b.c.

^ See above, Vol. I. p. 261.

STATES OF INSECTS.

from the leaf, to which she has previously applied it, to
a proper length, when the gluten becoming sufficiently
solid she wholly quits the egg,) the eggs are planted in
groups of ten or twelve on the surface of leaves and twigs,
jfi-om which they project like so many small fungi, to some
of which they have a remarkable resemblance. When tlie
included larva has made its way out of them by foi'cing
open the top, they look like little vases, and were actually
once figured by a Naturalist, as we learn from lleaumur,
as singular parasitic flowers growing upon the leaves of
the elder, for the origin of which he was extremely puz-
zled to account*. Eggs similarly furnished with a pedicle
are also laid by other insects ; but as most of these have
been before alluded to, it is not necessary to describe them
here^. The cause of these differences of form is for the
most part concealed from us : in many instances it may
perhaps be referred to that will to vary forms, and so to
glorify his wisdom and power, independently of other
considerations, which, as Dr. Paley has well remarked**,
seems often to have guided the Great Author of Nature.
But in some cases the end to be answered is sufficiently
evident. The long footstalks of the eggs of the Heme-
rohius just mentioned, there can be little doubt, are meant
to place them out of the reach of the hosts of predaceous
insects which roam around them, from whose jaws, thus
elevated on their slender shaft, tliey are as safe as the

* Reaum. iii. 386 — . t. xxxii./. 1. /. xxxiii./. 5.
I allude to OjiMon luteum F. {Ichneumon L.) Vol. i. Ed. 3.
p. 269. figured Plate XX. Fig. 22; and the Hydrachnce or Trom-
bidia. See above, and De Geer vii. 1 45.

"= From this circumstance called Tto'Kvvotx.i^os aocpiee, by the Apostle,
Ephes. iii. 10.

Nat. Theol. 11th Ed. 375.

STATES OF INSECTS.

eggs of the tailor bird in its twig-suspended nest from
the attack of snakes. Reaumur has described the eggs
of a kind of fly, common upon the excrements of the
horse and other animals {Scatophaga vulgaris Latr.), or
one related to it, that requires to be immersed in the dung
to which it is committed, on which the future grubs are
to feed. He found that if not thus surrounded with
moisture, they infallibly shrivelled up and came to no-
thing ; but it is equally necessary that they should not be
wholly covered : if they were, the young larva would be
suffocated at its first exit fi-om the egg. In what way is
this nice point secured ? In this manner. Each egg is
provided at its upper end, at which the animal when
hatched comes out, with two diverging horns ^; these
prevent it from being stuck into the excrement, in which
the female deposits the eggs one by one, more than three-
fourths of its length : and when examined they resemble
not badly, as Reaumur remarks (except that their colour
is white), a parcel of cloves stuck into a pudding, as they
are neatly inserted at due distances in the disgusting
mass^. The French Naturalists found these eggs in
swine's dung ; I have observed them in cow-dung. La-
treille thmks that the bristles above described attached
to the eggs of Nepa and Ranatra have a similar use, as
the female plunges them all but these bristles into the
stems of aquatic plants : but may not this have some-
thing to do with their oxygenation? Reaumur has
figured another egg of a dipterous insect which has a
longitudinal wing or lateral margin attached to it, giving

» Plate XX. Fig. 19. a a.
b Reaum. iv. 376—. t. xxvii./. 9, 10.
Hist. Nat. gen. et j)artic. des Crust, et Ins. xii. 283.

STATES OF INSECTS.

it the form of an oblong square, the object of which, he
conceives, is to give a greater surface by which it may
be more firmly fixed to the substance against which the
fly attaches it*.

Besides these more striking variations in figure, their
surface, though often smooth, is fi'equently curiously
and most elegantly sculptured^ a circumstance that di-
stinguishes the eggs of no other oviparous animals. Some,
as the margined egg just mentioned, are only sculptured
on one side, the other being plain ; or, as those of the
Tusseh silk-worm*^ {^Attacus Paphia) and other Bomhyces^
which have orbicular depressed eggs with a central ca-
vity above and below, have their circumference crossed
with wrinkles corresponding with the rmgs of the inclosed
embryo*^. Others agam are sculptured all over. Of
these, in some, the sculpture of the two sides is not sym-
metrical, as in those of a fly figured by Reaumur^ : but
in general there is a correspondence in this respect be-
tween the different parts of the egg. In tliose elegant
ones before alluded to of some bird-louse attached to the
golden pheasant, the shell resembles the purest wax, and
is scored with longitudinal striae, each distinguished by
a series of impressed points, which give it a beautiful ap-
pearance of net-work. In the others, as in a common
butterfly [Hipjmrchia jEgeiia) a.nd moth [Geometra era-
t(Bgata\ the whole surface is covered with hexagonal re-
ticulations ^ Others, as those of another buttei-fly {Hip-

» Reaum. iv. 381. /. xwi./. 19, 20.

Roxburgh in Linn. Trans, vii. 34.
' Some of the Koctvxe have sunilar eggs, as N. Lappa. Sepp iv,
t. m.f. I.e. d Reaum. vbi suj^r.f. 22, 23.

' Plate XX. Fig. 6. 8.

VOL. III. H

STATES OF INSECTS.

parchia Hyperanthus), are besei with minute granules or
tubercles ^ Others again, like those of the cabbage and
hawthorn butterflies {Pieris BrassiccB and Cratagi), are
remarkable for beautiful longitudinal ribs, often connected
by elevated lines crossing them at right angles ^ ; and in
some, as in another butterfly {Hipparchia Furtina), crown-
ed by imbricated scales ^ Many other minor differences
in this respect might be noticed, but these will suffice to
give some idea of the infinite variety exhibited in this
respect by these little atoms. If the Creator has wrought
them with so much art and skill, can it be beneath his
reasonable creatures to examine and admire them, that
they may glorify those attributes which they serve to il-
lustrate?

Some eggs after exclusion occasionally become slightly
corrugated : Malpighi supposed that this occurs only
when the eggs are barren, having observed that those of
the moth of the silk-worm which preserved their plump-
ness always produced caterpillars, while those which lost
their original rotundity and became wrinkled were con-
stantly unprolific. Bonnet, however, found exactly the
reverse take place in another moth^ so that these ap-
pearances are scarcely to be depended upon. Kuhn as-
serts, that a virgin female of the puss-moth [Cei-nra
Vinula) having begun to lay eggs, which were yellow
above, green below, and depressed, he introduced to her
an hour afterwards a male, and some minutes subse-
quently to the union, she again deposited eggs, which
were ^^ holly of a dark brown and convex =.

a XX. Fia. 5. ^ Ibid. Fxo. 3. 4 7. 9^c.

^ Ihifl. Fia. ir). Bonnet CEwr. n. 9. ^atrnf. xm 320.

S'l'A'I'KS or I XSKCTS.

vii. Colour. The colour of the eggs of insects is as va-
rious us their shape and sculpture. They are very often
white, those of some spiders like minute pearls some
are yellow, as those of the silk-worm ; others orange,
such are the eggs of the bloody-nosed beetle ( Tmarcha
tejiebricosa) ; others again of a golden hue ; sometimes
they are of a sanguine red. I remember once being
much surprised at seeing the water at one end of a ca-
nal in my garden as red as blood : upon examining it
further I found it discoloured by an infinite lunnber of
minute red eggs, belonging probably to some dipterous
insect of the Tipulidan tribe. Thei'e are also eggs of
every intermediate shade between red and black ; some
again are blue and others green. They are not always
of whole colours, for some are speckled like those of
many birds, of which I can show you specimens, that
are also shaped like birds' eggs; these I think were
laid by a common moth [Odenesis potatoria); others are
banded with different colours — thus the blue ecfffs of tiic
lappet-moth [Gastropaclia quercifoUa) are encircled by
three brown zones'^; others are brown with a white
zone

Many eggs assume a very different colour after being
laid a few days. In general upon their first exclusion
they are white. Those of the chameleon-fly {Strati/omis
Chamceleon) which I once found in great numbers, ar-
ranged like tiles on a roof one laid pardy over another,
on the under side of die leaves of the water-plantain, from
white become green, and then change to olive green.
Those of the hemipterous enemy of the larch, more than

" ,V. Did. d'Hist. Nat. xvi. 245. ^ Reaiini. ii. 28G.

Plate XX, Fig. 11. Sepp t. iv.f. 2.

II 2

100 STATUS OK INSECTS.

once mentioned in this letter, are first mouse-coloured,
then they assume a reddish hue, and lasdy a blackish
one. Those of the gnat from white in a short time as-
sume a shade of green, in a few hours they are entirely
green, and at length become gray^ Those of the silk-
worm, which at first are of a yellow or sulphur colour,
acquire a violet shade. The eggs of that rare moth En-
dromis versicolor, are at first sulphur-coloured, then
green, next rose-coloured, and lastly blackish. The
colour of almost all eggs changes when they are near
hatching; but this change depends more frequently upon
the colour of the included larva, which appears through
the transparent shell of the egg, than upon any actual
alteration in the egg itself.

viii. Period of hatching. The general rule for the
hatching of the eggs of insects is the absorption by the
embryo of all the superabundant moisture included in
them; but the time varies according to the state of the
atmosphere, to the action of which they are subjected.
Like those of other animals, they require a certain degree
of heat for the due evolution of the included larva. This
heat in much the greater number of instances is derived
from the temperature of the air, but often also from
other sources. The eggs of the gad-fly tribe are hatched
principally by the heat of the body of the animal to which
they are committed ; and doubtless the vital heat of va-
rious larvEe, small as it may be, must contribute some-
thing to the hatching of the eggs deposited in them by
various Ichneumons. In the fermenting bark in which the
instinct of the rhinoceros beedes {O^-yctes nasicorms 8cc.)

» Reaum. iv. 617.

STATES OV INSECTS.

101

impels them to place theirs, the dung which the Scara-
baidce select for that purpose, and the decaying vegeta-
bles chosen by many other insects, a degree of artificial
heat must exist : and the eggs, or rather egg-like pupas,
of the spider-fly of the swallow [Ornithomyia Hirimdinis)
are hatched by the heat of those birds which sit upon
them along with their own eggs.

Fabricius says, " Insects never sit upon their eggs* ;"
but certainly, as I formerly related to you*', the female
earwig does this, and one would be induced to suppose,
from the circumstance of the you g ones following their
mother, as chickens do the hen, that Pentatoma grisea
[Cimex Linn.), formerly mentioned, may do the same'^.

With these exceptions, the eggs of all insects are
hatched by atmospheric heat alone, the variations in
which determine the more speedy or more tardy disclo-
sure of the included insect. The eggs of such species as
have several broods in the year, as the nettle butterfly
( Vanessa Urticce), when laid in summer are hatched in a
few days ; but if not laid till the close of autumn, they
remain dormant through the winter, and are only hatched
at the return of spi'ing. That this difference is to be at-
tributed to the influence of heat has been often proved
by experiment: the autumnal eggs if brought into a
warm room may be hatched as soon as those laid in the
height of summer. Silk-worms' eggs naturally are not
hatched till they have been laid six weeks, but in coun-
tries where they are reared, the women effect their ex-
clusion in a much shorter period by carrying them in
their bosoms : yet to retard their hatching with particu-

» Philos. Ent. 76. •> See above, Vol. I. 358—.

See above, Vol. I. Ibid.

102 STATES OF INSECTS.

lar views is in many circumstances impossible. Wlien
tlie heat of the atmosphere has reached a certain point,
the hatching cannot be retarded by cellars ; and M.
Faujas has remarked, that in June the silk-worm's eggs
would hatch in an ice-house ^

The period of exclusion does not, however, depend
solely upon temperature: the hardness or softness of the
shell, and possibly differences in the consistence of the
included fluid, intended to serve this very purpose, cause
some eggs to be hatched much sooner than others exposed
to the same degree of heat. Thus the eggs of many flesh-
flies are hatched in twenty-four hours ^ those of bees and
some other insects in three days; those of a common
lady-bird {Coccinella hipunctata) in five or six days;
diose of spiders in about three weeks; those of the mole-
cricket in a month; while those of many Lepidoptera and
Coleoptera require a longer period for exclusion. The
hard eggs o{ Lasiocainpa Neustria and castrensis, noticed
above,''remain full nine months before being hatched S
as do those of another moth {Hypogymna dispar), which,
thoucrh laid in the beginnmg of the warm month of Au-
gust," do not send forth the included caterpillar till the
April following''. We know no more of the cause of

" Young's France, ii. 34. This author asserts, that no art will
hatch the eggs of the common silk-worms the first year, or that m
"nch they-m-e laid; but that there is a sort brought from Pej-sja
ich are hatched three times a year, and which will hatch in fif eu
Zys in the proper heat. In 1765, it is said, the common sort hatched

in the first year. Ibid. 226—. n i a,.

i In the V. Diet. cVHist. Nat. xii. 564. the eggs of the flesh-fly
are sail to hatch in two hours. This is true I believe n. very warm

weather. • i.ji

. I3rahm.310. - Rimrod iS^«/t»/. xv,. 131.

STATES Ol" JNSJiCTS.

103

this difference than of that which takes place in the
period of exclusion of the eggs of the different species of
birds.

Some eggs change considerably both their form and
consistence previously to being hatched. M. P. Huber
found that those of different species of ants when newly
laid are cylindrical, opaque, and of a milky white ; but just
before hatching their extremities are arched, and they
become transparent with only a single opaque whitish
point, cloud, or zone, in their interior*. An analogous
change takes place in the eggs of many spiders, which
just before hatching exhibit a change of form corre-
sponding with that which the included spider receives
when its parts begin to be developed, the thin and flexible
skin of the egg moulding itself to the body it incloses

In proportion as the germe included in the egg is ex-
panded, it becomes visible through the shell when trans-
parent: tliis is particularly the case with spiders, in
which, as was before observed, every part is very di-
stinctly seen. At length, when all the parts are consoli-
dated so as to be capable of motion, which in spiders
takes place in four or five days after they begin to be
visible in the egg, the animal breaks the pellicle by the
swelling of its body and the movement of its legs, and
then quits it, and disengages all its parts one after the
other In general, at least where the shell is harder
than that of spiders, insects make their way out by
gnawing an opening with their mandibles in the part
nearest their head, which, when the shell is very strong
(as in Lasiocampa Neiistria, &c.), it is often several

" Fonrmis. 69. ^ De Geer vii. 195. Ibid. 196.

104

STATES OF INSECTS.

hours in accomplishing \ In many uistances, however,
the larva is spared this trouble, one end of the egg being
furnished with a litde lid or trap-door, which it has but
to force up, and it can then emerge at pleasure : such
lids are to be found in the eggs of several butterflies and
moths, as Satyrus Mcera, Saturnia pavonia major, &c.
and the common louse''. In diose exquisitely elegant
eggs, before described, of some kind of bird-louse {Nir-
mus) found adhering to the base of the neck feathers of
the golden pheasant^, there is a lid or cap of this kind
of a hemispherical form terminating in a tortuous style.
Those of a species of bug {Pentatoma Latr.), found by
our friend the Rev. R. Sheppard, besides a convex lid
are furnished with a very curious machine, as it should
seem, for throwing it off. This machine is dark-brown,
of a corneous substance, and of the shape of a cross-bow "^j
the bow part being attached to the lid or pushing against
it, and the handle, by means of a membrane, to the upper
end of the side of the egg.

When the included animal has made its way out of
the egg, it enters upon a new state of existence, that of
Larm, to which I shall direct your attention in the fol-
lowing letter.

* Reaum. ii. 167.

Brahm. 249. Rosel. iv. 130. Swamm. Bibl. Nat. t. If. 2.
= By Mr. White, jun. corclwainer at Ipswich.

Plate XX. Fig. 16. a.

LETTER XXX.

STATES OF INSECTS.

LARVA STATE.

The Larva state is that in which insects exist imme-
diately after their exclusion from the egg (or from the
mother in ovo-viviparous species), in which they usually
eat voraciously, change their skin several times, and have
the power of locomotion, but do not propagate.

Almost all larvae, at their birth, are for a time in a very
feeble and languid state, the duration of which differs in
different species. In most it continues for a very short
time, a few minutes or perhaps hours, after which they
revive and betake hemselves to their appropriate food.
In others, as in the generality of spiders, this debility
lasts for seven or eight days, and in some species even a
month, during which the young ones remain inactive in
the egg-pouch », and it is not till they have cast their first
skin that their active state of existence commences.
All larvce may be divided into two great divisions : —

I. Those which in general form more or less re-

semble the perfect insect

II. Those which are wholly unlike the perfect in-

sect.

» De Geer vii. 197.

lOG

STATES Ol' JNSKCTS.

I shall begin by calling your attention to the charac-
ters of the Ji'rst of these divisions : the second, which is
by far the most numerous, will be afterwards considered.

1. Thejrst division includes the larvae of Scorpioiis,
Spiders, Coch'oaches, Grasshoppers, Lanthorn-Jlies, Bugs,
&c. ; or generally, with the exception of the Flea and
Crustacea, the whole of the Lhmean Orders Aptera and
Hemiptera. All these larvae, however remotely allied in
other respects, agree in the general similarity which they
bear to the perfect insects which proceed from them.
The most acute entomologist, untaught by experience,
could not even guess what would be the form of the
perfect insects to be produced from larvae of the second
division, while they can recognise the form of the spider,
the cricket, the cockroach, the bug, and the frog-hopper,
in that of the larvae. There are, however, dilFerences in
the degrees of this resemblance, according to which we
may, perhaps, divide this tribe in their second state as
follows : —

i. Those that resemble the perfect insect, except in

the relative proportions and number of some
of their parts.

ii. Those which resemble the perfect insect, except

that they are apterous, or not yet furnished

with organs of flight,
i. Spiders, Phalangia, scorpions, lice, Podura, sugar-
lice [Lepisma), mites, centipedes, millepedes, &c. come
under t\iQ first subdivision. The larvae of the first six
tribes here mentioned differ at their birth from the per-
fect nisect, only in size and the proportions of their parts.

STATIiS Ol' INSECTS. 107

Thus the larvae of spiders luivc their legs of a different
relative length from that which they subsequently ac-
quire ; and the palpi in the males, which previously to
the discoveries of Treviranus were regarded as their
sexual organs, are not yet fully developed ^ : and a si-
milar difference takes place in the legs of Phala?igia.
The general form too of the body undergoes slight alter-
ations, and the colour very considerable ones, widi each
change of the skin— a change to which all these tribes
are subject.

The larvae of the three last-mentioned tribes (the
mites, centipedes, and millepedes) differ from the per-
fect insect not only in the proportion but also in the
number of their parts. Leeuwenhoeck states (and De
Geer confirms his assertion, extendmg it to other species
of mites''), that the common cheese-mite, which in its
perfect state has eig/it legs, when first excluded from the
egg has but six, the third pair being wanting Some
however are born with eight legs, for instance J. eruditus
of Schrank, which he saw come from die egg itself with
that number''. Others again have never more than six
legs: this is the case with Latreille's genera — Cam,
Leptus, Atoma, and Ocyjoetes of Dr. Leach In the
centipedes {Scolopendridce) and millepedes {lulidce) dif-
ferences still more remarkable, as I have stated in a for-
mer letter, have been observed by De Geer ; these ani-
mals, in their progress to the perfect state, not only gain
several additional pairs of legs, but also several additional
segments of the body. This illustrious Entomologist found
that Pollyxenus lagurus {Scolopendra L.) was born a hexa-

» De Geer xii. 197. '' Ibid. 85. " Epist. Ixvii. 1694. 390,
Enum. Ins. Austr. 57o. " y. Diet. d'Hut. Nat. i. 74.

108

STATUS OF INSKCTS.

pod, with but three segments and as many pairs of feet,
but successively acquired five additional segments with
other appendages, and nine more pairs of feet ^. A spe-
cies of millepede [lulus terrestris L.), which he also
traced from its birth, and which begins the world at first
with only eight segments and six feet, by a successive
development at length acquires, in its perfect state, 50
segments and not less than 200 feet^. The nature of
these very singular accretions, which Latreille and Mr.
Wm. MacLeay have also observed in the centipedes *=,
seems not well understood. If, as is most probable,
though De Geer could not find any exuvi'as % the larva
cast a skin before each change, they do not essentially
differ from the metamorphosis of other insects. The
legs that these insects thus acquire are affixed to the
abdomen, the six that they set out with being attached
to the part representmg the trunk, so that the former
may be regarded as analogous to the prolegs of cater-
pillars. These animals therefore, as I have before inti-
mated, invert the order of Nature, and from perfect de-
generate into imperfect insects.

ii. If you examine the cochroach, cricJcet^ or grasshop-
per^ in different stages of their growth, you will find that
the larva does not vary essentially from the perfect insect,
except in wanting wings and elytra. The case is the
same in almost all the Linnean genera of the modern
order — Hemiptera ; and with Baphidia^ Termes, and
Psocus, in the Neuroptera. Some of these, however, ex-

» De Geer vii. 576. " Ibid. 584.

" Consider at. Gener. 21. Hor(B Entomolog. 353.
De Geer, Tbid. Mr. W. MacLeay observes of the Ckilopoda, or
Centipedes, that they moult in the manner of Crndacea. ubisupr. 352.

STATUS OF INSECTS.

109

hibit slighter discrepancies in the proportion of some of
their parts, but without affecting the general resemblance.
Thus the larvae of the common ear- wig have at first only
eighty and subsequently nine joints to their antennae,
whereas the perfect insect has fourteen''; and the forceps
is quite different, resemblmg rather two straight styles
than what its name implies. In those also of many bugs
{Cm-eus marginatiis F. &c.), the joints of the antennae are
of a shape dissimilar to that which obtains in the perfect
insect. In that of the common water-scorpion, the anal
air-tube, which is so long in the miago, is scarcely visi-
ble ^ In the Cicada tribe, so celebrated for their song %
neither the larva nor the imago have the enormous thigh
armed below with strong teeth, the tibiae terminating in
a fixed incurved claw, probably for the purpose of dig-
ging the holes into which they retire till they disclose the
fly, which distinguish the pupae of some species, and is
particularly conspicuous in one commonly bi'ought from
China'*. These often exhibit also other minor differences.

II. In treating of the second great division of larvae,
those that are wholly unlike the parent insect, — which
includes, with few exceptions ^, the whole of the Linnean

» De Geer iii. 549. The figure of the forceps in De Geer (Ibid.
/. XXV./. 21) is not quite correct. The styles do not taper to a point,
but are filiform and acute.

Compare De Geer iii. t. xviii./. 2 and 12. q.
See above, Vol. II. p. 401.
^ Plate XVI. Fig. 4. c. Reaum. v. t. xix./. 16. De Geer ubi supr.
t. xxxii./. 26. According to Reaumur, the larva as well as the pupa
of Chermcs Ficus has wing-cases (iii. 353).

" These are in the female sex of some Colcoptera, as Lampi/ris, Sec,
which retain in the perfect state nearly the same form which they
had when larvse. The lar\'£e of some Staphylini are not very dissi-
milar in form to the perfect insect.

110 STATES OF INSECTS.

orders, Coleoptera^ Lepidoptera, Hymenoptera, Diptera,
the majority of the Neiu-optera, Coccus and Aleyrodes in
Hemiptera, and the genus -P?^/^^' in Aptera,—! shall ad-
vert to their characters, under several distinct heads; and
to avoid unnecessary circumlocution, I shall in what fol-
lows wholly leave out of consideration the^Vs^ division
already explained, and use the term lam with reference
only to those of the second. The heads under which I
propose to treat of them are : The substance of their body,
its parts, shape, or figure, clothing, colour. Also the
Economy or mode of life of these creatures : their /oor/,
moultings, grovoth, age, sex, and their preparations for as-
suming the Pupce.

i. Substance, with the exception of the head and six
fore-feet, which are usually corneous, the exterior inte-
gument or skin of larvae is commonly of a membranous
texture, and the body is of a much softer consistence
than in the perfect insect. In those, however, of some
Stophylinida and other Coleoptera, the dorsal part of
the three fii'st pieces, which represent the trunk of the
perfect insect, is hard and horny. Some also have their
whole skin coriaceous, as the tortoise-shell butterfly
{Vanessa polychloros) ; and some few, as the wire-worm
{Elater segetum), and other Elateres, very hard. I pos-
sess a very remarkable larva from Brazil, from the ex-
treme flatness of its body, and from its having cavities to
receive its legs when unemployed, probably living under
bark, the skin of which is still harder than that of the
grub of the Elaters. Perhaps it has to resist great
pressure; and on tliat account is gifted with this quality,
so seldom to be met with in other kinds of larvns. The

STATES OF INSECTS.

Ill

interior of the body of these animals is- generally of a
softer consistence than in the perfect insect. Their in-
testines, and other internal organs, are usually wrapped
in a voluminous substance of a fatty nature, which is re-
garded as analogous to the epiploon^ omentum^ or caul,
which envelops the viscera of quadrupeds, &c., and is
called by Reaumur the corps graisseux. The use of this
general flexibility of larvae is obvious ; for, their bodies
being mostly long and narrow, a hard rigid covering
would have been very inconvenient, and a considerable
impediment to their motions. When a caterpillar is
feeding, it has occasion to apply its body to any part of
the margin of a leaf so as to support itself by its prolegs,
and when moving it wants to give it all the curves that
are necessary to enable it to avoid obstacles, and thread
its way through the sinuous labynnths which it must
often traverse. On the other hand, the hardness of the
substance of its head affords a strong fulcrum to the
muscles which keep its powerful jaws in constant play.
The larvje, indeed, of some Dtptera have a membra-
nous head; but their mandibles, which serve also as
legs, are not grinders, but merely claws, the muscles of
which require less powerful support Under this head
it may be proper to observe, that generally larvae are
opaque ; but some, as those of ants, and a few Lepido-
ptera^, are diaphanous. That of Corethra crystallina
^ Tipxda De Geer) is so beautifully transparent as to re-

^ The lai-vae described in the first Section, which resemble the
imago, are usually covered with a skin not materially different from
that of the insect in that state.

Huber Faurmu. 73; N. Diet, d'llist. ^at. vi. 250.

112

STATES OF INSECTS.

semble a piece of crystal, and scarcely to be distinguished
from the water in which it lives ^.

ii. Parts. The body of each larva consists of the head,
including its different organs, and of the succeeding seg-
ments, of which the three first may usually be denomi-
nated the tnmk, and have the six anterior feet, when
present, attached to their under side : the remainder is
the abdomen. The latter includes in some species a vari-
able number of membranous feet, as well as various ap-
pendages affixed usually to its tail and sides. No larva
is ever furnished with wings ^ Each of these greater
divisions, and the organs which they include, require
separate consideration.

1. Head. This, as was lately observed, is exteriorly of
a horny substance, or at least harder than the rest of the
body, in most larvae; and on this account, though rarely
separated from it by any visible distinct neck % is, if the

^ Reaum. v. 40. t. vi./. 4—15.

>> MuUer, the Danish zoologist, relates, that he once met with a
papilio which, with the true wings of the genus, had a head without
antennsE or tongue, furnished with mandibles; and, in short, that o. a
true caterpillar. It was a female, which deposited eggs that proved
barren. If this solitary instance was not a mistake, is it possible that
some parasitic larva had devoured only the inclosed head of the but-
terfly, or so injured it that it could not reject the hard skin of the
larva, and yet not be destroyed ?

"= The only larvae which have a visible distinct neck are those of
some Dythci, Staphjlini, and a few others, in which this part is quite-
distinct : proving the erroneousness of the opinion of those German
entomologists, who consider the thorax as analogous to the neck of
other animals, and hence call it Halsschilcl In some lepidopterous
larvffi, however, as in that of Pierk BrassiccB, though no visible neck
presents itself, one is very perceptible when the insect stretches the
head forward considerably. Reaimi. i. 460.

STATES OF INSECTS.

113

larva be of a tolerable size, distinguished at the first view.
In those of many Dipterous insects, however, the head is
covered with die same flexible membranous skin with the
rest of the body, from which it is often scarcely to be di-
stinguished. In these, except that it contains the organs
of manducation, it wears no more the appearance of a
head than any other segment of the body, and scarcely
so much as the last or anal one. The head of these larvae
is also remarkable for another peculiarity, — that it is ca-
pable of being extended or contracted, and assuming dif-
ferent forms at the will of the insect : a property which
the head of no superior animal can boast. It is probable
that there is a considerable variety in die shape and cir-
cumstances of the heads of larvae ; but since, with the ex-
ception of those of Lepidoptera, they have had less at-
tention paid to them than they deserve (indeed in a vast
number of cases, from the difficulty of meeting with them,
these variations, except in a few instances, have not been
described), I will here mention a few of the most remark-
able. The head of the young larva at its first exclusion
from the egg is usually the most dilated part of the body,
but it does not often continue so. In that of Cicindela
campestris, however, — the beautiful green beetle some-
tunes found in sandy banks, — and also in several cater-
pillars of Lepidoptera, it is much larger than any of the
following segments » ; which, in conjunction with the
animal's formidable jaws, gives it a most ferocious ap-
pearance. In some lepidopterous larvae the head is of
the same diameter with the rest of the body, but in in-
sects m general it may, I think, be stated as less; and

" Plate XVII. Fig. 13.
VOL. III. I

IH. STATES OF INSECTS.

occasionally it bears no proportion whatever to it. This
is the case with the subcortical one from Brasil lately
mentioned. It is more commonly longer than broad ;
but in some, as in the larvae of carrion beetles [Silph^s],
the reverse of this takes place. Its shape varies from
triangular to orbicular, the mouth of the animal forming
the vertex of the triangle. In some larvae of Hemerobii,
however, the head is narrowest behind. That of the grub
of a gnat noticed above {Corethra crystallina) forms a
kind of sharp horn or claw, terminating the body ante-
riorly ^ The contour of the head of larvae is usually
intire and unbroken ; but in the caterpillars of some Lepi-
doptera, as the butterfly called the grand admiral ( Vanessa
Atalanta), the Glanville fritiUary {Melitaa Cinxia), &c.
it is divided into two lobes K In the Brazil flat larvae it
is trilobed, each lateral lobe being divided into three
smaller ones : in which circumstance it somewhat resem-
bles the head of some subcortical Cimicida. Although
the part we are treating of is generally without horns,
yet in some tropical butterflies of the tribe of Npnphales,
it is singularly armed with them. Thus Papilio Anchises
is distinguished, according to Madame Merian S by two
in the occiput, which it has the power of retracting. In
the purple highflier {Apatura Iris), a British species, the

a Reaum. v. t. vi.f. 7. i-c , u

b In fact, in almost all Lepidopterous larvas the head may bere-
earded as divided into two lobes or eye-shaped portions, which in-
clude in the angle formed by their recession anteriorly from each
other thenasnsicfypeusF.), the labrum, and other instruments oi
manducation. Posteriorly these lobes generally come mto contact;
but I have a specimen in which there is a narrow space between

them.

Tnx. Surinam, t. xvn.

STATES or INSECTS.

115

two lobes of the head, I am mformed, terminate behmd in
two horns ; as they do hkewise in the brilliant Morpho
Menelmis the lobes assimiing the form of a pear, and
the horn representing the stalk. In a caterpillar I found
amongst Mr. Francillon's larvae, the head is bilobed,
with a very long recurvmg subcapitate subramose spine.
In Satynis Cassia:^ the head is armed with three occipital
stout spines The larva of Nymphalis Amphinome Latr.
[Limenitis F.) is crowned with a coronet of eight occipi-
tal stout acute spines, the intermediate ones being the
longest ; and that of Morpho Teucet' has a similar coro-
net, consisting of only seven blimt rays, seemingly, rather
tlian spines ^. With regard to the articulation of the
head with the trunk, it is generally by its 'whole diame-
ter ; but in some instances, only by a part of it. This is
the case with one of a sphinx figured by Mad. Merian ^;
and I have another, probably belonging to the nocturnal
Lepidoptera {Phaltena L.) ^. In both these, the head is
vertical and triangular ; and in the latter (which is a re^-
markable creature, the tail itself being more like a head,
and furnished with what resemble two prominent black
eyes) the vertex of the triangle is considerably higher than
the back of the animal. Whatever may be the clothing of
the body, the head is usually naked. Sometimes, however,
it is itself beset with very small simple spines, as in the but-
tei-fly of the mallow [Hesperia Malvce) ; or witli longer
compound ones, such as are found on the rest of the body.

" Ins. Surinam, t. liii. ^ Ibid. t. xxxii. ' Ibid. t. viii.
Ibid. t. xxiii. « Ibid. t. xiv.

' I purchased this singular caterpillar from the collection of the
late Mr, Francillon, with his other exotic larvae; but without any
indication of the fly to which it belonged.

I 2

116 STATES OF INSECTS.

This is the case wifli one of a butterfly named by Rosel
Papilio morsa. The most common colour of the head of
larvae, where it differs from the rest of the body, is a
darker or hghter reddish brown, or piceous. Tliis is
particularly observable in those of Coleopterous insects,
but it is very commonly in other tribes of the same hue.
Sometimes, amongst the Lepidoptera, the head is of a
different colour from the rest of the body; especially
where a contrast renders it striking. I can show the ca-
terpillar of some insect, probably of the hawk-moth tribe
{Spliingida), from Georgia, remarkable for the length of
its anal spine, in which the body is black, and the head
red: another has a white head and a brown body. In
the larvae of some Lepidoptera, Coleoptei-a, und Diptera,
the head can be wholly or nearly withdrawn within the
first segment of the body. This may be readily seen in
that of the common glow-worm; and that of a small gnat
{Tiptda replicata De Geer) withdraws it so completely
that the anterior margin of that segment closes the ori-
fice, so that the animal appears to have no head ^—
The parts of the head which require distinct considera-
tion are, the eyes, antennce, and the mouth : consisting
of various organs, which will be specified. Some of these
parts and organs are peculiar to larvae of one order,
others to those of another, and some are furnished with
them all.

Eyes. The larvae of many insects have no eyes. Those
with antennae which terminate in a lamellated clava
^Scarahcms L.), and Capricorn beetles also {Ccramhyx L.),

■•> De Geer vi. 353.

STATES OF INSECTS.

117

amongst the Coleoptera^ ai'e without them, and probably
several others; and amongst the Diptera, all those with
a membi-anous or vai'iable head. Those of the remain-
ing orders, with the exception, perhaps, of some Hymen-
optera and Lepidojotera, are furnished with these organs;
and in the Coleoptera all the predaceous tribes, as well
as most of those that are herbivorous or granivorous,
and the Gnats and other Tipulidans {Tipulariae Latr.) in
the Diptera, are also distinguished by them. In the lar-
vae of the dragon-flies {Libellula L.), and other Nmro-
ptera, they are composed of many facets as in those of
the perfect insect, from which they differ chiefly in being
smaller. But in the other insects of this description they
are simple, and resemble those of the Arachni da, and
many aptera. These simple eyes vary in their number,
in different genera and tribes, from one to six on each
side of the head. Thus the larva of Telephorus, and the
saw-flies, has only one that of Cicindela three, the two
posterior ones being large with a red pupil surrounded
by a paler iris, which adds to the fierce aspect of this
animal; and the anterior one very minute. Those
of the tortoise-beetles also {Cassida) have three^ ; of
Staphjlinus,foiir ; of Timarcha (the bloody-nosed beetle)
Jive; of Carabus, and the Lepidoptera in general, six.
In the last they are of different sizes, and generally ar-
ranged in a circle: in that of Hemerohius there are five in
a circle, with one central one The appearance of these

» De Gecr iv. 66. ii. 922.

•> De Geer v. 170.
Dc Geer says, he could not make out the number of eyes of the
larva of the whirlwig {Gyrinus): probably, as in that of Dylhcus,
there art six. iv. 392. 385.

118

STATES OF INSECTS.

globules, which are often not visible but under a power-
ful lens, is so different from that of the eyes of a butter-
fly or moth, or other perfect insect, that it has been
doubted whether they actually perform the office of eyes,
but without reason. They occupy the usual station of those
organs, being situated in many instances upon a protube-
rance which appears to incase them ; and seem of a con-
struction closely analogous to that of the eyes of spiders,
and the stemmata or ocelli of Hynienoptera, which have
been satisfactorily proved to be organs of vision. In the
larva of a moth not yet ascertained to exist in this coun-
try, Attacus Tau, and probably other species, the eyes,
after the skin has been changed a few times, are no longer
to be seen ^.

Antenncs. Most larvas are provided with organs near
the base of the mandibles, which from their situation and
figure may be regarded as antennte. Fabricius has as-
serted that the larvae of the s2cw-^\qs {Tenthredo L.) have
no antennae; but in this he was mistaken, for though
very short, they are discoverable in them, as he might
have learned by consultmg De Geer^. In the majority
of Neuropterous larvae, they almost precisely resemble
those of the perfect insect. In all the rest they are very
different. The antennae of Coleopterous larvae are usu-
ally either filiform or setaceous, consisting of four or five
joints, nearly equal in length. Those of Lepidopterous
larvae are commonly conical, as are those likewise of
Chrysomela and Coccinella &c. amongst the Coleoptera,
and very short, composed of two or three joints, of Avhich
the last is much thinner than the first, and ends in one or

" Fez. 188, " ii. 923, /. xxxvi./. 4, b b. Fabr. Pluhs. 'Enl. 60.

STATES OF INSECTS. 119

two hairs or bristles. These antennae the larva has the
power of protruding or retracting at pleasure. Lyonnet
mforms us, that the caterpillar of the great goat-moth
{Cossus Ugnijjerda) can draw the joints of its antemias one
within the other, so as nearly to conceal the whole*.
The larva of the common gnat has two long mcurved se-
taceous antennae, fringed with hairs at some distance from
their apex, which consist only of a single joint The
greater number of Dipterous larvae, however, all indeed
except the Tipulidans {Tipidarice Latr.), and many be-
longing to the Coleopta-a and Hymenoptera orders (as
tiiose of Curculio, Apion, Apis, &c.), are wholly deprived
of antennse. It is a general rule, that the antennae of
larvse are shorter than the same organs in the perfect in-
sect, the tribe Ephemerina perhaps affording the only
example in which the reverse of this takes place

Mouth. All larvse have a mouth situated m the head,
by which they receive their food, and furnished with one
or more instruments for the purpose of mastication and
deglutition. These instruments, in all the orders except
Lepidoptei-a, some Neuroptei-a and Diptera, bear a ge-
neral resemblance to the same parts in the peifect insect.
In larvae of the Coleopterous, Lepidopterous, and Hy-
menopterous orders, we can distinguish for the most part
an upper and under lip ; two pairs of jaws answeruig to
the mandibulae and maxillse ; and two, four, or six pal-
pi'': and some of these instruments may be found in
most Diptera. Each of these parts require separate no-
tice.

Upper-lip (Labrum). The mouth of almost all larvae,

Lyonnet 41. 1. c. ^ De Geer vi. 307.

<^ Ibid. ii. t. xvi. Conip.y; 2 a a with /. 14 aa.
In the larva of Cicindda there arc sa- palpi, as in the perfect insect.

120

STATES OF INSECTS.

except some of the order Diptera, are provided with a
distinct upper-lip, for retaining their food during masti-
cation. As the constrviction of this part does not widely
differ from that of the perfect insect, which will hereafter
be more fully described, it is only necessary to observe,
that it is usually a transverse moveable plate, attached
posteriorly to the nasus {clypeus F.), and situated just
above the mandibles ^.

Upper-Jaws (Mandibul^e). The most usual figure of
these, which are of a hard horny consistence ^, is that of
two slightly concave, oblong, or triangular plates, often
at their lower extremity of considerable thickness, and of
very irregular form, the base of which is filled with
powerful muscles, and planted in the side of the mouth
so as to move transversely. The other extremity can be
made to meet or diverge like the claws of pincers, and
are divided into one or more tooth-like indentations, by
means of which the food of the larva is cut This is
their construction in the larvae of all Lepidoptera, and m
many of those of the , other orders. They frequently,
however, assume a different form, though their situation
is always the same. Thus m the larvae of the Capricorn
beetles [Ceramhyx L.) and of other wood-boring species,
they are shaped like the half of a cone, the inner sides of
which, applying close to each other, form a pair of power-
ful grindstones, capable of comminuting the hardest tim-

a Lyonnet, t. If. 7. e. In the larva of Callidium violaceum, how-
ever, this part is of a singular shape, being orbicular. Kirby Linn.
Trans, v. t. xii./. 12. a.

b It is affirmed {N. Diet. d'Hist. Nat. vii. 333) that the larvae of
those Coleoplcra that live in cai-cases have mandibles ahnost mem-
branous : those, however, of that of Si/i}/ia rugosa are horny and
hard.

Lyonnet, /. ii./. 1. d d, and/. 2, 3, 4.

STATES OF INSECTS. 121

ber ^. M. Cuvier has observed, with regard to the man-
dibulse of those of stag-beetles (Lucanus), that besides
their teeth at the extremity, they have towards their base
a flat striated molary surface ; so tliat they both cut and
grind their hgneous food It seems to have escaped
him, that a similar structure takes place in many perfect
insects of the lamellicorn tribe, as I shall hereafter show
you. In the larvae of the water-beetles {Dytiscus L.),
ant-lions {Myrmeleon L.), and lace-winged flies {HefnerO"
bins L.), they resemble somewhat the forceps at the tail
of an ear-wig, being long and incurved; and, what is more
remarkable, hollow and perforated at the end, so as to
serve as a channel for conveying into the larva's mouth
the juices of the prey which by their aid it has seized.
Reaumur even asserts, that the larva of Myrmeleon has
no other entrance into its throat than through these tu-.
bular mandibles ^. That of the rove-beetles {StapJiy-
linus L.), and of many other Coleopterous genera, have
these organs of this forcipate construction, without being
perforated^. In the larva of the carnivorous flies, and
many other Diptera, are two black incurved subulate
parts, connected at the base, and capable of being pro-
truded out of, and retracted into, the head, through the
skin of which they are usually visible. As I informed
you in a former letter % these mandibles are used for
tsoalking as well as feeding : they are parallel to each
other, and are neither formed for cutting nor grinding

" Kirby in Lmn. Trans, v. t. xii./. 7 l>.
^ Cuvier Anat. Comp. in. 322. <" Reaum. vi. 340.

The larva of Cichidda camjiesbis has mandibles of this descrip-
tion. Plate XVII. Fig. 1.3. cc.
" See above, Vol. II. 275—..

122

STATES OF INSECTS.

like the mandibles of other insects, but merely detach
particles of food by digging into it and tearing the fibres
asunder. In this operation they are probably assisted by
an acutely triangular dart-like instrument of a horny sub-
stance, which in some species {Miisca vomitoria) is
placed between the two. In others this part is wanting.
Some Dipterous larvae have two similar mandibles, but in-
stead of being parallel, they are placed one above the other;
others (M^sm domedica and meridiana) have but one such
mandible, and some have no perceptible mandible of any
kind. The mandibles of thelarvaof the crane-flies (
which are transverse and unguiform, do not act against
each other, but against two other fixed, internally con-
cave and externally convex, and dentated pieces ^

Under-ja-jos (Maxillje). These are a pair of organs,
usually of a softer consistence, placed immediately under
the upper-jaws; but as they are usually so formed and si-
tuated as not to have any action upon each other, it is
probable that m general they rather assist in submitting
the food to the action of the mandibulse, than in the com-
minution of it. In Lepidopterous larvae they appear to
be conical or cylindrical (at least in that of the cossus
so admirably figured by Lyonnet ^), and to consist of two
joints; which may, I imagine, be analogous to tlie upper
and lower portions of which the maxillae of perfect insects
usually consist. The last of these jomts is surmoimted
by two smaller jointed palpiform organs. If any part of
the maxillae can act upon each other, it is these organs
or palpi ; but it is evident they are not calculated for mas-
tication, although they may assist in the retention of the

a Reaum. v. 9. t. If. i.cc.ll. " Traile Anatom. t. ii./. 1. «

STATES 01' INSECTS. 123

substance to be masticated. In a figure given by Reau-
mur of the under side of the head of another lepidopte-
rous larva ( Erminea Pomonella), the maxilliE consist of
a single joint, and appear to be crowned by chelate pal-
pia circumstance which is also observable in that of a
common species of stag-beetle [Lucanus parallelipipedus),
the weevil of the water-hemlock {Lixus paraplecticus
and other insects. In general the maxillae of larvae are
without the lobe or lobes discoverable in those of most
perfect insects, this part being usually represented by a
kind of nipple, or palpiform jointed process, strictly ana-
logous to the interior maxillary palpi of the predaceous
coleoptera; but in most of the lamellicorn beetles the
lobe exists in its pi-oper fonn as it does likewise in that
of the capricorn-beetle before noticed {Callidium viola-
cetm^). In the former instance, it is armed with spines or
claws; but in the latter it is unarmed, and rounded at tlie
end. In the larva of Cicindela campestris, the base of the
maxilla runs in a transverse direction fi'om the mentum,
to which, as is usually the case, it is attached. From this
at right angles proceeds the lobe, from the outer side of
which the feeler emerges ; and the inner part terminates
in an unguiform joint, ending in two or three bristles.
Tlie structure in the larvae of water-beetles {Dytiscus L.)
is different, for they appear to be without maxillae ^; but
the case really seems to be, that these organs are repre-
sented by the first joint of what M. Cuvier calls their
2mlpi from which proceed the real palpi, the interior

" Reauni. ii. t. 40./. 4. ^ De Geer v. 229.

" Ibid. iv. t. xi./. \G.pp. Linn. Trans, v. L xii./. 10.

Cuvier Anat. Comjy. iii. 323.
' De Geer iv. xv./. 9. b b. The exterior and interior palpi ai-e
both represented in this figure.

121.

STATES OF INSECTS.

one being very short, and consisting only of a single
joint. These maxillae of larvae were regarded by Reau-
mur and other writers as parts of the under-lip, on each
side of which they are situated ; and indeed, as well as
those in the perfect insect, they form a part of the same
machine, being connected by their base with the mentum,
which is part of the labium, but they are clearly analo-
gous to the maxillae of the imago. They are not to be
found in the larvae of many Dipterous insects, and per-
haps in some species belonging to other orders. In some
Neuropterous larvae, as those of the Libellulina MacLeay,
the maxillae are of a substance quite as solid and horny as
the mandibles, which in every respect they resemble ^

Under-lip (Labium). Between the two maxillae in the
larvae of most of the insects under consideration is a part
termed by Reaumur the middle division of the under-lip,
but which is in fact analogous to the whole of that organ
in the imago. This organ varies in shape, being some-
times quadrangular, often conical, &c. Interiorly it is
frequently connected with a more fleshy protuberance,
called the tongue by Reaumur ^ and supplying the place
of the ligula in the perfect insect. On each side of the
apex of the under-lip is a minute feeler, and in the mid-
dle between these in the Lejncbptera and many others, is
a filiform organ, which I shall caU the spinner-et {Fusuhis),
through which the larva draws the silken thread em-
ployed in fabricating its cocoon, preparatory to assuming
the pupa state, and for other purposes ^. This organ is

a Reaum. vi. t. xxxvii./. 5. e c. ' Ibid i. 125.

« Plate XXI Fig. 9. The oi;i>an with which the larvae of Hcmc-
robius, Mnrmcleon, and Hydroplnlus, spin their cocoons, is situated
in the anas. The spinneret of the Cossus is figured by Lyonnet Ana^
lom.t. n.f. l.L, and

STATES OF INSECTS. 125

found only iii those larvae which have the power of spm-
ning silk ; that is, in all Lepidoptcra, most Hymenoptera,
Trichoptera, some Neuroptera^ and even a Dipto-om in-
sect ^. This tube, Lyonnet had reason to believe, is com-
posed of longitudinal slips, alternately corneous and mem-
branous, so as to give the insect the power of contracting
its diameter, and thus making the thread thicker or
smaller. There is only a single orifice at the end, which
is cut obliquely, somewhat like a pen, only with less obli-
quity, and without a point, the opening being below, so
as to be conveniently applicable to the bodies on which
the larva is placed. Reaumur conceived that this spin-
neret had two orifices ; but Lyonnet ascertained this to
be a mistake, the two silk tubes uniting into one before
they reach the orifice. From the contractile nature of
the sides and the form of the orifice, combined with the
power the insect has of moving it in every direction, re-
sults the gi-eat difference which we see in the breadth and
form of the threads, some being seven or eight times as
thick as others, some cylindrical, others flat, others chan-
nelled, and others of different thickness in different parts ^
In the larvae of many Diptera the under-lip is merely a
small tubercle, which can be protruded fi'om the insect's
mouth by pressure

One of the most remarkable prepensile instruments, in
which the art and skill of a Divine Mechanician are
singularly conspicuous, and which appears to be widiout
a parallel in the insect world, may be seen in the under-
lip of the various species of dragon-fly {Lihcllula L.). In

* De Geer vi. 370. This species {Tipula Agarici seticomis De Gcer)
has two separate spinnerets, t. xx./. 8. m m.

" Lyonnet 55—, c Rcauni. iv. IGG.

126

STATES or INSECTS.

Other larvae this part is usually small and inconspicuous,
and serves merely for retaining the food and assisting in
its deglutition; but m these it is by far the largest organ
of the mouth, which when closed it entirely conceals ;
and it not only retains but actually seizes the animal's
prey, by means of a very singular pair of jaws with which
it is furnished. Conceive your under-lip (to have re-
course, as Reaumur on another occasion to such com-
parison,) to be horny instead of fleshy, and to be elon-
gated perpendicularly downwards ^, so as to wrap over
your chin and extend to its bottom,— that this elongation
is there expanded into a triangular convex plate S at-
tached to it by a jomt so as to bend upwards again and
fold over the face as high as the nose, concealmg not
only the chin and the first-mentioned elongation, but the
mouth and part of the cheeks ^ : conceive, mbreover, that
to the end of this last-mentioned plate are fixed two other
convex ones, so broad as to cover the whole nose and
temples f,— -that these can open at pleasure, transversely
like a pair of jaws, so as to expose the nose and mouth,
and that their inner edges where they meet are cut into
numerous sharp teeth or spines, or armed with one or
more long and sharp claws s :— you will then have as ac-
curate an idea as my powers of description can give, of
the strange conformation of the under-lip in the larvae of
the tribes of Libellulina ; which conceals the mouth and
face precisely as I have supposed a similar construction
of your lip would do yours. You will probably admit

a Reaum. v. 155. " Ibid. vi. t. xxxvii./. 7- bp. Ibid, m c e.
d Ibid./. 6. p. ^ Ibid. Compare/. 4 with/. 6, 7.
f Ibid. xxxvi./. 12. s 2{ e. . . ,

e Ibid. V e, and xxxviii./7, dc.;De Geer ii. t. x,x./ 1/. d g.

STATES OF INSECTS.

127

that your own visage would present an appearance not very
engaging while concealed by such a mask ; but it would
strike still more awe into the spectators, were they to see
you first open the two upper jaw-like plates, which would
project from each temple like the blinders of a horse ;
and next, having by means of the joint at your chin let
down the whole apparatus and uncovered your face, em-
ploy them in seizing any food that presented itself, and
conveying it to your mouth. Yet this procedure is that
adopted by the larvae provided with this strange organ.
While it is at rest, it applies close to and covers the face.
When the insects would make use of it, they unfold it
like an arm, catch the prey at which they aim by means
of the mandibuliform plates, and then partly refold it so
as to hold the prey to the mouth in a convenient position
for the operation of the two pairs of jaws with which they
are provided. Reaumur once found one of them thus
holding and devouring alarge tadpole; — a sufficient proof
that Swammerdam was greatly deceived in imagining
earth to be the food of animals so tremendously armed
and fitted for carnivorous purposes. Such an under-lip
as I have described is found in the tribe of dragon-flies
{Libellulina) ; varied, however, considerably in its figure
in the different genera. In the larva of Libellula Fab.,
such as Libellula depressa, &c. it is of the shape above
described ; so exactly resembling a mask, that if Ento-
mologists ever went to masquerades, they could not more
effectually relieve the insipidity of such amusements and
attract the attention of the demoiselles, than by appearing
at the supper table with a mask of this construction, and
serving themselves by its assistance. It would be difficult,
to be sure, by mechanism to supply the place of the mus-

128

STATES OF INSECTS.

cles with which in the insect it is amply provided : but
Merhn, or his successor, has surmounted greater obsta-
cles. In the larva of the Fabrician jEshnce [JLiihellula
grandis, &c. L.), this apparatus is not convex but flat :
so that, though it equally conceals the face, it does not so
accurately resemble a. mask ; and the jaws at its apex are
not convex plates, but rather two single conical teeth
It is, as to its general shape, similarly constructed in
Agrion Fab. [L. Virgo, &c. L.); but the first joint is
more remarkably elongated, the jaws more precisely re-
semble jaws than in any of the rest, and are armed with
three long, very sharp teeth : between them also there is
a lozenge-shaped opening, through which, when the ap-
paratus is closed, is protruded a circular sort of nipple,
apparently analogous to the ligida ^. Lihellula ccnea, L.,
which is the type of another tribe [Cordulia Leach), has
a mask somewhat different from all the above, the jaws be-
ing armed with a moveable claw and an internal tooth
You will admire the wisdom of this admirable contri-
vance, when you reflect that these larvas are not fitted to
pursue their prey with rapidity, like most predaceous
animals ; but that they steal upon them, as De Geer ob-
serves '^j as a cat does upon a bird, very slowly, and as if
they counted their steps ; and then, by a sudden evolu-
tion of this machine, take them as it were by surprise,
when they think themselves safe. De Geer says, it is
very difficult for other insects to elude their attacks, and
that he has even seen them devour very small fishes
« Reaum. vi. t. xxxvii./. 4— G. 8.

" Ibid. t. xxxviii. Fii-st joint/. 8. bfp. ; jaws/. 7- c d.; opening o,
Ligula /. 6. /.

De Geer ii./. 17, Jaws g g ; claw ; tooth ^ ibid. 674.
Ibid. ii. G74.

STATES OF INSECTS.

129

As these animals are found in almost every ditch, you
will doubtless lose no time in examining for yoursell' an
instance of so singular a construction.

Feelers (Palpi). In the orders Dipta-a and Hymeno-
ptera are many larvte in which these organs have not
been certainly discovered; yet Reaumur in that of a com-
mon fly (M. meridiana L.) found four retractile nipples *
which seem analogous to them ; and Latreille has ob-
served, that below the mandibles of those of ants are
four minute points, two on each side'': but in all other
larvae their existence is more clearly ascertained. The
maxillm-y palpi vary in number, many having tns:o on
each maxilla and others only one. In the perfect msect
the former is one of the distinguishing characters of the
predaceous beetles {Entomophagi Latr.), but in the larvae
it is more widely extended; since even in the catei*pillars
of Lepidopta-a the inner lobe of the maxilla which re-
presents this feeler is jointed, which is precisely the case
with the beetles just named. Cuvier lias observed this
circumstance in the larva of the stag-bcede <=; and it be-
longs to many other Colcoplera that have only a pair of
maxillary palpi in die perfect state. The labial palpi are
always two, emerging usually one on each side from the
apex of the under-lip. With regard to the form of the
palpi, those of the Lepidoptera are mostly conical ; in
odier orders they are sometimes setaceous and some-
times filiform. Their termination is generally simple,
but sometimes the last joint is divided. They are for the
most part very short, and the labial shorter tlian the

» Rcaum. iv. 37C.
Anat. Comp. iii. 322,

VOL. III.

•> N. Diet. d'Hist. Nat. xii. 64.

130 STATES OF INSECTS.

maxillary. The latter never exceed four joints % whicli
seems the most natural number; and the former are limit-
ed to three. Both vary between these numbers, and one
joint. The joints, though commonly simple, are sometimes
branched. This is the case with one I met with in con-
siderable numbers upon the Turnip, in October 1808,
the second joint of the palpi of which sends forth near
the apex an internal branch. In the larva of the Cossus,
as Lyonnet informs us^ the joints of the palpi are re-
tractile, so that the whole of the organ may be nearly
withdrawn.

After thus describing the head of larvre, and its prin-
cipal organs, we must next say something upon the re-
mainder of the body, or what constitutes the

2. Tr^mlc and Abdomen : which I shall.consider under
one article. These are composed of several segments or
rings, to which the feet and other appendages of the
body are fixed. The form of these segments, or that of
their vertical section, varies considerably: in many Lepi^
doptera, the wire-worm, &c., it would be nearly circular;
in others a greater or less segment of a circle would re-
present it; and in some, perhaps, it would consist of two
such segments applied together. Their lower surface is
generally nearly plane. Their most natural number,
without the head and including the anal segment, is
.twelve: this they seldom exceed, and perhaps never
fourteen. The three first segments are those which re-

- a At first in the Dytisci they appear to have five joints ; but, as 1
before observed, the first joint must be regarded as rcpresenung the

maxilla,;
^ Lyonnet Analom. 55, 58,

STATES OP INSECTS.

151

present the trunJc of the perfect insect, and to which the
six anterior legs when present are affixed. In general^
they differ from the remaining segments only in being
shorter, and in many cases less distinctly characterized ;
but in Neuropterous larv£e, those of Dj/tisci, and some
other Coleoptera, they are longer than the succeedmg
ones, and pretty nearly resemble the trunk of the animal
in its last state. The surface of the trunk and abdomen
will be considered under a subsequent head ; I shall not,
therefore, describe it here. The coiiformation of the dif-
ferent segments varies but little, except of the terminal
one, or tail, which in different larvae takes various figures.
In most, this part is obtuse and rounded; in others acute
or acuminate ; in others truncate ; and in others emaro-i-
nate, or with a wider sinus, and with intermediate modifi-
cations of shape which it would be endless to particularize.
In some, also, it is simple and unarmed ; in others be-
set with horns, spines, radii, and tubercles of different
forms, some of which will come under future considera-
tion. The parts connected with the trunk and abdo-
men which will requii-e separate consideration, are the
legs, the spiracles, and various appendages.

Legs. It may be stated generally that the larva- of the
orders Coleoptera, Lepidoptera, and Neuropitera, have
legs ; and that those of the orders Hymenoptera and Di-
ptera have none. This must be understood, however,
with some , exceptions. Thus the larvae of some Coleo-
ptera, as the weevil tribes (Curculio L.) have no legs, un-
less we may call by that name certain fleshy tubercles be-
smeared with gluten, which assist them in their motions =»;

" De Geer v. 203;

K 2

132 STATES OF INSECTS.

while those Tenthredo and Sirex in the order Hyvien-
optera are furnished with these organs. At present I
know no Dipterous larva that may be said to have real
legs, unless we are to regard as such certain tentacula
formed upon a different model from the legs of other lar-
vae^^ Rosel has, I think, figured a Lepidopterous apode.
No Neuropterous one has yet been discovered.

The legs of larvae are of two kinds ; either horny and
composed of jomts, or fleshy and without joints \ The
first of these, as I observed in a former letter S are the
principal instruments of locomotion, and the last are to
be regarded chiefly as props and stays by which the ani-
mal keeps its long body from trailing, or by which it
takes hold of surfaces; while the other legs, or where
there are none, the annuli of its body, regulate its mo-
tions. The former have been commonly called true legs
{pedes veri\ because they are persistent, bemg found in
the perfect insect as well as in the larva; and the latter
spurious legs {pedes spurii), because they are caducous,
being found in the larva only. Instead of these not very
appropriate names, I shall employ for the former the
simple term legs, and for the latter p7-olegs {propedes)
, The legs, when present, are always in number six, and
attached by pairs to the underside of the three first seg-
ments of the trunk. They are of a horny substance, and
consist usually of the same parts as those of tlie perfect

" De Geer iv. 5, Legs of this kind are figured Plate XXIII.

b In the larva, however, of Sialis, or some kindred genus, in which,
Hke those of Scolopendra, the prolegs are jointed, a pair distioguishes
each abdominal segment. See Reaum. iv. U xv./. 1 , 3. Compare De
Geer ii. t. xxiii./. 11.

« See above, Vol. IL 286—. Ibid. 288.

STATES Of INSECTS.

133

insect; namely, coxa, troclianter, femur, tibia, and tarms,
suspended to each other by membranous ligaments: these
parts are less distinctly marked in some than in others.
Thus in the legs of a caterpillar, or the grub of a capri-
corn-beetle, at first you would think there were only three
or four joints besides the claw; but upon a nearer inspec-
tion, you would discover at the base of the leg the rudi-
ments of two others *, in the latter represented indeed by
the fleshy protuberance from which the legs emerge.
In the larvae of the predaceous Coleoptera, the hip and
trochanter are as conspicuous nearly as in the perfect
insect; and the tarsus, which still consists of only a sin-
gle joint, is armed with two claws''. In those of the
Nairoptera order, in which all the joints are very con-
spicuous, the tarsi are jointed, as well as two-clawed *=.
The legs of larv£B are usually shorter than those of the
perfect insect, and scarcely differ from each other in
shape, for they all gradually decrease in diameter from
the base to the apex. This is the most usual conforma-
tion of them in Lepidopterous, Hymenopterous, and
some Coleopterous larvae, (those of the capricom-beetles
are very short and minute, so as to be scarcely visible,)
m which they are so small as to be concealed by the body
of the insect In Neuropterous larvae, however, and

» Lyonnet Anatom. t. m.f. 8. Coxa b. Trochanter c. Femur d. Ti-
bia E. Tarsus f. Claiv g,

De Geer iv. t. xiii./. 20; and t. xv.f. 16.

<= Ibid. ii. t. xvi./. 5,6,7.dc: and xix.f. i.efgh.

^ The larva of a scarce moth {Stauropus Fagi. See Plate XIX.
Fig. 4) is an exception to this. The first pair of its legs are of the
ordinary stature, but the two next are remarkably long, and so thin
and weak as to be unable to bear the body. Pezold. 119. Another
minute caterpillar described by Reaumur has the thii-d pair of tbe

134; STATES OF INSECTS.

several Coleoptera, as those of Djjtiscus, Staphylinus, Coc-
cinella, &c., they more resemble the legs of the perfect
insect, the joints being more elongated, and the femoral
one projecting beyond tho body ^.

You will find no other than true legs in most Coleo-
pterous, Neuropterous, and Hymenopterous larvae. But
those of the saw-flies {Tenthredo L.), and all caterpillars,
have besides a number of prolegs : a few Dipterous larvae
also, are provided with some organs nearly analogous to
them. These prolegs are fleshy, commonly conical or
cylindrical, and sometimes retractile protuberances, usu-
ally attached by pairs to the underside of that part of
the body that represents the abdomen of the future fly^.
They vary in conformation and in number ; some having
but one, others as many as eighteen.

With regard to their conformation, they may be di-
vided into two principal sections: first, those furnished
with terminal claws; and secondly, those deprived of
them. Each of which may be divided into smaller sec-
tions, founded on the general figure of the prolegs, and
fvrrangement of the claws or hooks.

tegs apparently fleshy and singularly incrassated at the apex. into a
pyrifonn figure, terminated by a pair of claws. This conformation
is for some particular purpose in the economy of the animal, since
they are the most busily employed of all in arranging the threads of
her web. Reaum. ii. 358. In the larva of a geometer {Gcomctra lu-
luina) the third pair are remarkably long. Illig. Mag. 402. In that
of another moth, according to Kuhn {Naturf. xvi. 78. tAv.f. 3), the
third pair of the fore-legs is remarkably incrassated, being twice as
thick and long as the other pair, though consisting of the same num-
ber of joints, the last of which has claws.

On the legs and prolegs see also what is said above, V ol. 11,

p. 286— .

^ In some few inbtancctf these legs are dorsal. Ibid. 281.

STATES OF INSECTS.

135;

i. The proI(3gs of almost all Lepitlopterous larvae are
furnished with a set of minute slender horny hooks, crotr
chets, or clam, of different lengths, somewhat resem-
bling fish-hooks; which either partially or wholly sur-
round the apex like a pallisade. By means of these
claws, of which there are trom forty to sixty in each
prole^ a short and a long one arranged alternately, the
insect is enabled to cling lo smooth surfaces, to grasp
the smallest twigs to which the legs could not possibly
adhere: a circumstance which the flexible nature of
the prolegs greatly facilitates ^. Claws nearly similar
are found on the prolegs of some Dijiterous larvjE ^, but
not in any of those of the other orders. These last, how- '
ever, are seldom either so numerous, or arranged in
the same manner, as in caterpillars. Wh.en the sole of.
the foot is open, the claws with which it more or less
surrounded are turned outwards, and are in a situation
to lay hold of any surface ; but when the animal wishes
to let go its hold, it begins to draw in the skin of the sole,

^ The claws or crotchets, though general, are not universal, iu
Lepidopterous laiTse. An exception is furnished to the rule by the
singular limaciform ones of Hejnalus Testudo and Asellus of Fabricius,
two moths forming Haworth's genus Apoda, which have no distinct
prolegs, but in their stead a number of small transparent shining tu-
bercles without claws. The larva also of one of the subcutaneous
moths first discovered by De Geer in the leaves of the rose (i. 446),
but whose history is fully given by Goeze, Naturf. xy. 37 — 4S, (who
has satisfactorily ascertained that it is the true larva of a Tinea of
Linne, but of a different habit from that of most subcutaneous ones),
has no true legs, and eighteen prolegs without any claws. Another
subcutaneous larva, for the history of which we are indebted to
M. Godeheu de Riville, is according to him entirely deprived of legs
of any kind (Bonnet ix. 196 — .); as is another of the same tribe that
feeds on the poplar, an account of which is given by Goeze Xaliuf.
,\iv. 105. PpvTE XXIV. Fig. 7. See also below, p. 13/.

136 STATES OF INSECTS.

and in proportion this is retracted, the daws turn
their points inwards, so as not to impede its motion \

The prolegs with claws may be further divided into
four different kinds.

1. In the larvae of the great majority of butterflies
and moths they assume the form of a truncated cone,
the lower and smaller end of which is expanded into a
semicircular or subtriangular plate, having the inner
half of its circumference beset with the claws above men-
tioned; and, from its great power of dilating and con-
tracting, admirably adapted for performing the offices of
a foot. Jungius calls these legs pedes elephantini'", and
the term is not altogether inapplicable, since they exhibit
considerable resemblance to the clumsy but accommo-
dating leg and foot of the gigantic animal he aUudes to.

2. The larvae of many minute moths, particularly of
the Fabrician genera Tortrix and Tmm-those which
live in convoluted leaves, the interior of fruits, &c., as weU
as the Cossus, and some other large moths,— have their
prolegs of a form not very unlike those of the preceding
class, but shorter, and without any terminal expansion;
the apex, moreover, is wholly, instead of half, surround-
ed with claws «=; the additional provision of which, to-
gether with a centrical kind of nipple capable of being
protruded or retracted, m some measure, though imper-
fectly, supplies the place of the more flexible plate-hke
expansion present m the first class.

3. The third class is composed of a very few Lepido-
pferous larvae which have their prolegs very tliick and
conical at the base, but afterwards remarkably slender,

Lyonnct Anatom. 84. t. iii. /. 1 1 , 12.
b Hht. Ycrmmn, 13Q. ' Plate XXIII. Fig. 1.

STATES OF INSECTS,

137

long, and cylindrical, so as exactly to assume the shape
of a wooden leg These, as in the first class, are ex-
panded at the end into a flat plate : but this is wholly cir-
cular, is surrounded with claws, and has also in the mid^
die a retractile nipple, as in the preceding class. In
Cossiis, at least in an American species (Cossus Robinice),
described by Professor Peck ^, the anal prolegs have th§
claws only on their exterior half.

4. The remaining description of unguiferous prolegs,
if they may not rather be deemed a kind of tentacula,
are those of certain Diptera, provided with no true legs;
which differ from the three preceding classes, either in
their shape, or the arrangement of their claws. In
one kmd of those remarkable larvae, which from their
long respiratory anal tubes Reaumur denominates " rat"
tailed" that of Elophilus pendulus, there are fourteen of
these prolegs, affixed by pairs to the ventral segments,
the twelve posterior ones of which are sijbconical, and
truncate at the apex, which is surrounded with two cir-;
cles of very minute claws, diose of the inner being much
more numerous and shorter than those of the exterior
circle ; while the anterior pair terminate in a flat expan-
sion, and in shape almost exactly resemble those of a mole
The prolegs of the larvfe of a kind of gnat called by
De Geer Tipida amphibia, and of Syrphus mystaceus F.,
[Musca phimata De Geer,) are nearly of a similar con-
struction, but in the last are armed with three claws
only''. Long moveable claws also distinguish the sin-

» Plate XXIII. Fig. 1?.

^ Account of Locust-tree Insects, 69.
" Reauin. iv. 443. t. xxx./. G. //. t. xxii./. 6. / /,
Pc Geer vi. 383. and 137. /. viii./. 9:

138'. STATES OV INSECTS.

gular prolegs before described* of another gnat {Tani/-
pus maculatus Meig., Tipula De Geer). The case-worpis
{Trichoptera K.) and some others, have two prolegs at
the anus, each furnished with a single claw ^.

ii. The prolegs deprived of dam are found in the
larva of the Hymenopterous tribe of saw-flies ( Tenthredo
L.), in those of some Lepidoptera {Hepialns F. &c.), and
in some few Coleopterous and Dipterous genera. Those
of the former are of the shape of a truncated cone, and
resemble the second class of unguiculate prolegs, except
in the defect of claws. In the latter they are a mere re-
tractile nipple-like protuberance, in some species so small
as scarcely to be perceptible. In all they aid in progres-.
sive motion ; but it is by laying hold of surfaces, and so
enabling the body more readily to push itself forward by
annular contraction and dilatation, and not by taking
steps, of which all prolegs are incapable : to assist in this
purpose the protuberance sometimes secretes a gluten ^,
which supplies the place of clavys. Some larvae have the
power of voluntarily dilating pertain portions of the un-
derside of their body, so as to assume nearly the shape
and to perform the functions of prolegs. In a Coleopte-
rous (?) subcortical one from Brazil, before alluded to,
there are four round and nearly flat areas in each ventral. '
segment of the abdomen, but the last very litde raised
above the surface, and rough, somewhat like a file; and
besides these, the base of the anal segment has ten of
these little rough spaces, but of a different shape, beipg
nearly linear, placed in a double series, five on each side.
Doubtless these may be regarded as a kind of prolegSj

" See aboye, Vol. II. p. 278. Dc Gccr tibi supr.37G.

" gciium. iv. 184. I. XV./. IS, c c. ' Dc Gccr v. 203.

STATES OF INSECTS.

139

which enable the animal to push itself along between tlie
bark and the wood ^.

In considering, in the next place, the numher and si-
tuation of the prolegs, it will contribute to distinctness to
advert to these circumstances as they occur in the diffe-
rent orders furnished with these organs.

To begin with the Lepidopte^-a. — Lepidopterous larvae
have either ten, eight, six, or two prolegs, seldom more
and never fewer. Of these, with a very few exceptions,
two are attached to the last or anal, and the rest, when;
present, to one or more of the sixth, seventh, eighth, and
ninth segments of the body : none are ever found on the
fourth, fifth, tenth, or eleventh segments.

1. Where ten prolegs are present, as is the case in by
far the greatest proportion of Lepidopterous larvae, there
is constantly an anal pair, and a pair on each of the four
ijitermediate segments just mentioned.

2. In caterpillars, which like those of a few species of
the genera Sphinx, Pyralis, and of the Bombycidce, &c.
have eight legs, they are placed in three different ways. In
those which have an anal paii*, the remaining six are ii^.
some fixed to the sixth, seventh, and eighth ; in others, to
the seventh, eighth, and ninth segments. In those which,
like Caiira Viimla, and several other species of the
same family, have no anal prolegs; the whole eight
emerge from the sixth, seventh, eighth, and ninth seg-
ments.

3. The Hemigeometers, as Noctua Gamma, &c. have

? See above, p. HQ, 114.
Some few subcutaneous larvae have more, as that, before men-
tioned, observed by De Gecr in the leaves of the rose ; which has
dghteen prolegs, and no true ones.

JiO STATEB OF INSECTS.

only six legs : namely, an anal pair, and two ventral ones,
situated on the eighth and ninth segments.

4. The larvjfi of the Geometers {Geometric F.) have
but four prolegs ; of which two are anal, and two spring
from the ninth segment. It should be observed, how-
ever, that the larvae of Hemigeometers, and even of some
of those that have ten prolegs, where the four anterior ones
are much shorter than the rest, move in the same way as
tlie Geometers. This even prevails in a few where these
organs are all of equal length.

5. Many of the larvae of Tinea L. which live in the in-
terior of fruits, seeds, &c., have but one pair of prolegs,
which are attached to the anal segment.

6. The larvae of Haworth's genus Apoda [Hepialus
Testudo and Asellus F.), remarkable for their slug-like
shape and appearance, move by the aid of two lateral
longitudinal pustule-like protuberances, which leave a
trace of a gummy slime in their course.

Hymenoptera.—The larvas of the different tribes of
Tenthredo L., almost the only Hymenopterous insects in
Avhich prolegs are present, have a variable number of these
organs ; some sixteen, as the saw-fly of the willow (T. lu-
tea L.), and this is the most numerous tribe of them, m-
cluding the modern genera, Cimhex F., Ptci-opho7nis, &c.
Others have fourteen, as that of the cherry ( T. ccrasi L.);
and many others with only nine joints to their antennae.
A third class have only twelve, as that of the rose ( T. Ro-
sa L.), but this contains but few species. The last class
contains those that have no prolegs at all, but only the six
horny ones appended to the trunk. Of this ti-ibe, the
caterpillars of which have a very different aspect from
the preceding, are those of the genus Li/da F. (T. cry-

STATES OF INSECTS.

141

throcepJiala L.) Two of the prolegs are anal, and the
rest intermediate, and none are furnished with claws.
This circumstance, in conjunction with the greater num-
ber of prolegs, except in the case of Lyda^ will always
serve as a mark to distinguish these Jhnsses chenilles, as
the French call the larvte of saw-flies, fi om time caterpil-
lars. The dorsal prolegs of a species of Cyiiips described
by Reaumur have been before noticed.

Coleoptera, — The larvae of insects of this order are so
little known or attended to, that no very accurate gene-
ralization of them in this respect is practicable. Many of
them, in addition to their six hoi-ny legs, have a proleg
at the anus ; which in many cases appears to be the last
segment of the abdomen, forming an obtuse angle vidth
the remamder of it, so as to support tliat part of the body,
and prevent it from trailing ; and in some instances, as
in Ch-ysomela Poptdi, a common beede, secreting a slimy
matter to fix itself''. In the larvae of Staphylinida: this
proleg is very long and cylindrical ; in that of Ciciii-
dela it is shorter, and in shape a truncated cone rather
compressed; it is very short, also, in those of the Silpha
that I have seen. In the wire-worm {Elatei' Segetum) it
is a minute retractile tubercle, placed in a nearly semi-
circular space, shut in by the last dorsal segment, which
becomes also ventral at the anus. This space is in fact

* De Geer ii. t. xl.f. 15, 16. Bergman has added to these four
classes of the larvaj of saw-flies, a fifth ; the insects belonging to
which, he affirms, though they have sixteen prolegs, are without the
anal pair. Ibid. 931. But as neither De Geer nor Reaumur ever met
with one of this description, it is probable he was mistaken. Reaumur
thought he had seen one witli eighteen prolegs upon Eri/sivium alli-
aria (v. 91), but he does not speak positively.

^ Do Geer v. 288.

142 STATES OF raSECTS.

the last ventral segment. This seems characteristic of
the genus =». From the underside of the body of the
common meal-worm {Tenehrio Molilor), at the junction
of the two last segments, when the animal walks, there
issues a fleshy part, furnished below with two rather hardj
long, and moveable pediform pieces, which the animal
uses in walking ^. In the larva of another beetle, whose
ravages have been before noticed, under the name of the
cadelle'^ {Trogosita viauritanica\ a pair of prolegs are
said to be found under the anal segment; and in that of
the bloody-nose beetle ( Timarcha tenehricosa), that seg-
ment is bifid. That of tlie weevil of the common water-
hemlock {Lixm joaraplccticiis F.) exhibits a singular ano-
maly: prolegs occupy the usual station of the true legs,
V)eing attached to the three segments representing the
trunk This insect, however, does not appear to use
them in moving. A pair in each of die twelve segments
of the body are found in the grub of another weevil
{Hypera Rumicis Germ.), the nine last pair being the
shortest, which all assist the insect in walking ^ But the
greatest number of prolegs is to be found in the Brazil
subcortical larva lately mentioned. Besides the six horny
legs of the trunk, this remarkable animal has four pro-
legs on each of the seven intermediate abdominal seg-
ments, and five on each side of the base of the last,
making the whole number of prolegs, if so they may
be called, amount to forty-four: a far greater number
than is to be found in any larva at present known. When
I wrote to you upon the motions of insects, I informed

> De Geer iv. 157. ^^^<^- v-" 30. /• ii./. 1 1 •

See nbovc, Vol. I. p. 171. ' ^^^^cr v. 228.

^ Ibid. 23.3.

STATES OF INSECTS.

you that some larvae moved by means of legs upon their
back^*, but I was not then aware that any were furnished
with them both on the back and the belly at the same
time. By the kindness of Mr. Joseph Sparshall of Nor-
wich, a vei'y ardent and indefatigable entomologist, I am
in possession of the larva of Rhagmm fasciatum, a timbei-
feeding beetle. This animal on the ten intermediate seff-
ments of the underside of the body, which in the centre
form a fleshy protuberance, has on it a double series of
rasps, as it were, consisting each of two rows of oblique
oblong prominences ; and on the seven intermediate doi -
sal segments there are also in the centre seven rasps of
three or four rows each, of similar prominences : so that
this animal at the same time can push itself along both by
dorsal and ventral prolegs. It is worthy of observation,
that a pan- of these rasps is between the second and third
pair of true legs.

Diptei-a. — The larva of a little gnatj Tipula steirara-
ria De Geer^ {Chironovius'iAe\g.'^\ drags itself along by
the assistance of a single tubercle, placed on the under-
side of the first segment of the body, which the animal
has the power of lengthening or contracting That of
another beautiful Chiro7iomus {C. plumosus), remarkable
for the feathered antennje of the male has two short
prolegs, or pediform but not retractile tentacula in the
same situation ^ Others, as that of Tanypus maculatus,

» See above, Vol. II. p. 281. ^ He Geer vi. 388.

"= Ibid. .389. - Reaum. v. t. v./. 10.

' Ibid. 31. This larva has also a pair of pediform processes at the
anus, surrounded at the end with claws {t. v./. 4, 5, « s), which lie
saw the animal use in locomotion ; but which he suspects to be re-
spiratory organs (Il)id. 33), which Latrciile asserts they are. Gen.
Cni.it, ct Ins. iv. 249.

.i44« STATES OF INSECTS*

&c. liave /tt)0 pairs, one attached to the anal and the
other to the first segment K Tijnda amphibia De Geer
in this state has ten prolegs, placed by pairs on the fourth,
fifth, eighth, ninth, and tenth dorsal segments"; and
Scava Pyrastri F., one of the aphidivorous flies, has not
fewer than forty-two, arranged in a sextuple series, seven
in each row

It may not be useless to close this long description ot
the legs of larvae with a tabular view of them, founded
chiefly upon these organs; which afford very obvious
marks of distinction.

I. Larvae without legs.

i. With a corneous head of determinate shape (co-
leopterous and hymenopterous apods—Culicidce,
some Tipidida, &c. amongst the Diptera).

ii. With a membranaceous head of indeterminate
shape {Muscidce, SyrpUdcc, and other Diptera).

II. Larvae with legs.

i. With legs only, and with or without an anal pro-
leo- (Neuroptera, and many Coleoptei'a).

\ Joints short and conical {Elater, Ceramhyci-
da, &c.).

2. Joints long and subfiliform {Staphylinus,
Coccinella, Cicindela, &c.).

ii. Prolegs only (many Tipididce, and some subcu-
taneous Lepidopterous larvae, &c).

iii. Both legs and prolegs {Lepidoptera, Tenthredt-
nidce, and some Coleoptera).

1. Without claws {Tenthredinida:, &c.).

2. With claws {Lepidoptera, &c.).

a De Geer Ibkl. t. xxiv./. 15-17. " 383-

c Ibid. 111. t.s\.f. 14—10.

STATES OF INSECTS^

145

I should next say something upon the spiracles, or
breathing-pores, or any other external apparatus for the
purpose of respiration.^ in larvas; but I think it will be
best to reserve the consideration of these for a subsequent
Letter. We will therefore conclude this detailed de-
scription of their parts in their first state, with some acr
count of their other

iii. Appendages. The generality of larvae have no other
external organs than those already described ; but: in se-
veral of them we observe various kinds of retractile ones
and others — ^protuberances — horn-like processes — rays,
&c. ; which, though not properly coming either imder
any of the above parts^ or under the clothing of these
animals, yet require to be noticed. Upon these I shall
now enlarge a little.

You must have observed upon the back of the last seg-
ment but one of the caterpillar of the silk-worm a horn-
like process, rising at first nearly perpendicularly, and
then bending forward. A similar horn, though confined
in the genus Bombyx to the silk-worm and a few others,
if we may believe Madame Merian, who, however, often
makes great mistakes, is found in the beautiful caterpillar
of one of the largest and finest moths that we know
{Erebus Strix the glory of tlie Noctuida;, and in most
of those of the hawk-moths {Sphinx F.) IS.^ Porcellus, Vi-
tis, and a few others excepted ; in some of which, as
S. Lahi-usccc, &c., this anal horn is replaced by a gibbo-
sity, and in others, as S. (Enothera;, by a callous eye-like
plate in the same situation, but much longer and

» Merian Ins. Sur. t. xx. Ibid. t. xxxiv.

<= I have a caterpillar, 1 believe from Georgia, in which this hortf
IS nearly an inch long, filiform, slender, and tortuous.
VOL. III. t

14.6

STATES OF INSECTS.

commonly curving backwards over the tail*. Some-
times, however, as in S. ocellata and S. Stellatarum, it is
perfectly straight. These organs towards the apex are
horny, and often end in a sharp point ; nearer the base
they are fleshy. They are without any true joint*', yet
the insect can elevate or depress them at pleasure. Un-
der a lens, they usually appear covered with spinous emi-
nences, arranged like scales. The use of these horns is
quite unknown : Goedart fancies that they secrete a po-
tent poison, and are intended as instruments of defence;
but both suppositions are altogether unfounded. It has
been remarked, that the body of those caterpillars which
have these horns, is firmer, and yields less to the touch
than that of those which have no such appendages The
larva of a small timber-devouring beetle {Lymexylon der-
mestoides F.) has, like the above caterpillars, a long horn,
and in the same situation : it has also a singular protu-
berance on the first segment Upon some other cater-
pillars, as mBomhyx Stigma F., a singular pair of horn-like
appendages arises from the back of the second segment of
the body, excludmg the head. In a tawny-coloured one
fi-om Georgia, with a transverse row of short black spines
on each segment, these horns are half an inch long,
black, covered with spinous eminences, rather thickest at
the base, and terminate in a little knob. They appear to
articulate with the body at the lower extremity. I have
another species, black, with narrow longitudmal yellow

» Plate XVIII. Fig. 12. c.

^ That of SpMiuv Iairo2)hce L. appears to be jointed, at least it is
moniliforni. Merian Surinam, t. xxxviii. Compare also /. iii.
N. Diet d'Hist. Nat. vi. 252.
Schellenberg Entomolog. Beyir. 1. 1.

STATES OF INSECTS.

147

Stripes, in which these horns are of equal thickness at
base and apex, but with the same terminal knob. Da-
nais Archippus has a pair of tentacula at the head, and
another paix*, but shorter, at the tail ; and D. Gylippus
has, besides these, two in the middle of the body

We are equally ignorant of the use of the upright horn
found upon the back of the fourth segment in the larva of
some moths {NocUia Psi, and tride7is F.) which is of a con-
struction quite different from that of those last described.
It is cyUndrical, slightly thmnpr at the apex, which is
obtuse, fleshy, mcapable of motion, of a black colour, and
about two lines long. On the same segment, also, in the
CBse-vforms {Trichoptera K.) are three fleshy conical emit
nences, which the animal can inflate or depress, so that
they sometimes totally disappear, and then in an instant
swell out again. When retracted, they form a tunnel-
shaped cavity, vai'ying in depth ^. Reaumur conjectured
that these eminences were connected witli respiration,
and one circumstance seems in favour of this conjecture,
that this segment has not the respiratory threads observ-
able in the subsequent ones. Latreille mentions certain
fleshy naked eminences placed upon the ninth and tenth
segments of some hairy caterpillars, which, like those just
mentioned, the animal can elevate more or less. They
are often Httle cones ; but when it would shorten them,
the summit is drawn in, and a tunnel appears where be-
fore there was a pyramid

In a former Letter I gave you a short account of the

" Smith's Abbott's Insects of Georgia, t, xiii.
" De Geer ii. 507. t. xi./. 16. m n. t. xiv./. 7.
" N. Diet. d'Hist. Nat. vi. 256.

L 2

14.8

STATES OF INSECTS.

remarkable Y-shaped, as it should seem, scent-organs
{Osmateria) of the beautiful caterpillar of the swallow-
tailed butterfly {Papilio Machaon L.), and others of the
Equites * ; I will now speak of them more fully. That
found in the former is situated at the anterior margin at
the back of the first segment, close to the head, from
which at first view it seems to proceed. At the bottom
it is simple, but divides towards the middle, like the let-
ter Y, into two forks, of a fleshy substance ^ which it can
lengthen, as a snail does its horns, to five times their or-
dinary extent, or retract them within the stalk, so as wholly
to conceal them. Sometimes it protrudes one fork, keep-
ing the other retracted ; and often withdraws the whole
apparatus for hours together under the skin, and its
place is only marked by two tawny-coloured dots, so that
an ordinary spectator would not suspect the existence of
such an instrument <=. Unfortunately this larva is rare
in this country, so that I can scarcely flatter you witli the
hope of seeing this curious organ in a living specimen ^,
unless you choose to import a parcel of its eggs from the
south of Europe, where it is common. This you will
think rather a wild proposition ; but why should not En-
tomologists impoit the eggs of rare insects, as well as bo-
tanists the seeds of rare plants? But if you will be satis-
fied with the dissection of a dead specimen, I have seve-

See above, Vol. II. p. 244—.
Plate XIX. Fig. 1. a.
<= Reaum. i. t. xxx./. 2. N. Diet. d'Hist. Nat. xxiv. 490, 49/--.
•1 Ray says he found it feeding on common fennel, about Middle-
ton in Yorkshire : Lett. 69. The indefatigable Mr. Dale recently
found many in the neighbourhood of Whittlesea-mere, feeding on
Selinum palustre. It will also eat the wild carrot.

STATES OF INSECTS.

14.9

nil, done by the ingenious Mr. Abbott of Georgia, in
which this part is well exhibited

Another small catei*pillar, as it should seem, of a geo-
meter, prepared by the same gentleman, exhibits a pair
of similar horns on the fifth and sixth segments : in these
the common base from which the fork proceeds is very
short and wide, and each branch grows gradually more
slender from the base to the apex, where it is involute.
Whether these are retractile, or whether they correspond
with those of P. Machaon in their nature and use, cannot
be ascertained fi'om a dead specimen : as they belong to a
larva of a quite different tribe of Lepidoptera, the proba-
bility is, that they essentially differ. Two globose re-
tractile vesicles issue from the ninth and tenth segments
of those of Arctia clvrysorrliea^ &c. ^

A great number of Lepidopterous larvae, particularly
those which are smooth and of a moderate size, have be-
tween the under-lip and fore-legs a slender transverse open-
ing, containing a teat-like protuberance of the same con-
struction as the furcate horn of the caterpillar of the beau-
tifid mountain-buttei-fly, Parnassius Apollo ; and, like that,
can either be wholly retracted and concealed, or by pres-
sure be extended to the length of one of the legs. In some
larvae this part is of a subhemispherical figure, generally
single, but sometimes double. It is commonly, however,
more slender and conical ; and when of this shape, it is
sometimes quadruple The use of this part is not very
clearly known : some have supposed it to be a second
spinneret, and to be of use in fabricating the cocoon; but

' This gentleman was remarkable for the admirable manner in
which he prepared caterpillars, so as scarcely to differ from life.
^ Reaum. i. 92. c Bonnet ii. 84—. iii. 1.

150 STATES OF INSECTS.

it is more probable that it secretes some other kind of
fluid, and is connected with defence.

The singular organ in a similar situation, evidently
for that purpose, with which the puss-moth endeavours
to annoy its assailants, has been described in a former
Letter, to which I refer you \ Bonnet, who was the first
that discovered this organ, ascertained that it might be
cut off without injury to either larva or imago. He also
remarked in a caterpillar found in the wild succory {Ci-
cliorium Intybiis) another short, biack, needle-shaped or-
gan between the conical part just described and the un-
der-lip ^. De Geer mentions a remarkable fleshy horn-
like style, which issues from the lower side of the first
segment, between the head and the legs of the case-worms
{Trichoptera) : he does not describe it as retractile, or it
might be regarded as analogous to those oi Lepidoptera
simUarly situated, that I have just noticed In that of
the emperor-moth {Saturnia Pavonia\ there are perfo-
rated tubercles, which when the animal is molested spirt
forth a transparent fluid

The horn-like appendage of the puss-moth {Centra Vi-
nula) is situated at the tail of the insect, and is composed
of two distinct cylindrical diverging branches, each about
four lines long, not united at the base. Each of these is
hollow, and includes a smaller cylindrical piece, which
can be protruded at pleasure, and withdrawn again, as a
pencil withm its case; or, rather, as the horns of a snail.
The two outer horns are tolerably firm, moveable at their
base, and beset with black spines; the interior tentacula
are fleshy, moveable in every direction, and in full-grown

a See above, Vol. II. 251~. ^ Bonnet ii. 88.

- De Geer ii. 507- 1. xi.f. 16. c. " Ros. iv. 16^.

STATES OF INSECTS.

151

larvce of a rose colour. The animal seldom protrudes
them, unless in some way disturbed ; and frequently it
approximates the two outer cases so closely that they re-
semble a single horn. It appears to use these inner horns,
when protruded, as a kind of whip to drive away the
flies, especially the Ichneumons, that alight upon its body.
When touched in any place, it will unsheath one of them,
and sometimes both, and with them strike the place where
it is incommoded A similar organ is found in some
other Bombycidce, as B. Tau and Furcula F. Reaumur
mentions a caterpillar that to this kind of tail added the
resemblance of two ears, or two cylindrical bodies, ter-
minating in a point, which emerged from the first segment
behind the head In another observed by the same au-
thor, the legs were replaced by a single horn, but which
did not appear to send forth an internal one : fi-om the
back of its fourth segment also emerged a single conical
or pyramidal fleshy eminence or cleft, terminating in two
points Some of the tropical butterflies also, as may be
seen in the figures of Madame Merian, have two diver-
ging anal horns instead of anal prolegs ; but it does not
appear that they incase tentacula'*. Wherever these
caudal horns are found, the above prolegs are wanting ^.

» De Geer i. 322—. See Plate XIX. Fig. 2. a a.
•> Reaum. ii. 275. t. xxii./. 3.
Ibid. 276. t. xxii./. 4, 5.

Ins. Surinam, t. vii. Nymphalis AmpJiinome xxiii. Morpko Teu-
cer t. xxxii. Papilio Cassice.

" This is not, however, universally the case, for the caterpillar of a
Geometer described by Reaumur (ii. 363. t. xxix./. 8.) (G. aviatorid)
has a paif of fleshy anal horns, terminating, it should seem from his
figure, in a minute hook that the animal uses as a forceps; which has
at the same time the anal legs, of which indeed these horns seem to
be appendages.

152

STATES OF INSECTS.

Two conical anal horns also distinguish the caterpillar
of one of the moths called Prominents, Nutodonta ca-
melina; but these are not terminal, but on the back of
the last segment but one^. In that of another Bri-r
tish moth, N. ziczac F., there are three dorsal promi-
nences, one near the anus, and two more iri the middle
Some Geometers (G. fuUginosa^ &c.) have two erect
horns on the eleventh segment, and others (G. syringaria,
&c.) two recurved ones on the eighth ^ I must not here
omit to mention the curious hooks emerging from two tu-
bercles on the back of the eighth segment of the ferocious
larva of that beautiful tiger-beetle, the Cicindela cavipe-
stris L., not uncommon on warm sunny banks. This ani-
mal with incessant labour, as we are informed by M. Des-
marets, digs a cylindrical burrow, to the enormous depth,
the size of the animal considered, of eighteen inches. To
effect this, it carries out small masses of earth upon its large
concave head; and having often occasion to rest in ascend-
ing this height, by means of these hooks ^ it fixes itself
to the sides of its burrow, and, having finally arrived at its
mouth, casts off its burthen. When these insects He in
wait for their prey, their head, probably in conjunction
with the first segment of the body, accurately stops the
mouth of the burrow, so as to form an exact level with
the slu-rounding soil ; and thus careless insects, walking
over it without perceiving the snare, are seized in a mo-
pient and devoured ^

Another kind of appendage, which is found m some

» Sepp. iv. t. l.f. 6 — 8.

b Plate XIX. Fig. 5. a b. Sepp. iv. t. xii./. 4—7.
e Ros.iii.G9. " Plate XVII. Fig. 13. c,

? N. Did. d'Hisl. Nat. vii. 95.

STATES OF INSECTS.

153

larvse, is the organ employed by them to carry the excre-
ment ; with which, instead of letting it fall to the ground,
they form a kind of umbrella to shelter and probably con-
ceal them. All the tortoise-beetles {Cassida L.) have in-
struments for this purpose, as well as an Indian genus
[Imatidium Latr.) very nearly related to them. This in-
strument is a kind of fork, half as long as the body, con-
sisting of two branches, growing gradually smaller frortt
the base to the summit, where they terminate in a very
fine point, of a substance rather horny, and attached to
the body near the anal orifice. They are armed on the
outside with short spines, from the base for about a third
of their length. When this fork, as it usually is, is laid
parallel to the back, with its points towards the head, the
anal aperture points the same way. When the animal
walks, the fork points the other way, and is in the same
line with the body, and the anus assumes a prone posi-
tion ^.

The larvae of a genus of flies {Volucella GeofFr.) re-
markable for inhabiting the nests of humble bees, are di-
stinguished on their upper side by six long, diverging,
pointed, membranous radii ; placed in a semicircle round
the anus'': what the particular use of these organs may
be, has not been conjectui'ed. Another in my collection
has only four upper radii, but below the anus are two
fleshy filiform tentacula. One of a Tipulidan described
by Reaumur, has also four upper teeth ; but instead of
two subanal tentacula, has six The singular larva of
another of this tribe {Chironomus 2>lumosus) has on the

» De Geer v. 170— l.'x.f. 19—23. Compare Reaum. iii. 235—,
" Plate XIX. Fig. 11. a. De Geer vi. 137- Reaum. iv. 482.
<^ Reaum. iv. t. xiv./. 9, 10,

154<

STATE>S OF INSECTS.

two last segments four long, fleshy, filiform, flexible ten-
tacula, often interlaced with each other ; which, accord-
ing to the same illustriovis author, are used by the ani-
mal to fix its caudal extremity, like the geometers, that the
other end may be at liberty. Besides these organs round
the anus, it has also four other oval ones, of uncertain
use : not to mention the two prolegs, which M. Latreille
thinks are air-tubes ^. Jointed anal organs are observ-
able in other larvae : those in that of a saw-fly described
by De Geer {Li/da F.) consist of three jomts ; in that
of Hister cadavcrinus, a carnivorous beetle, of two*=.
The larva as well as the pupa and imago of Ephemera
is furnished with three long diverging multiarticulate
tails, which are probably useful as a kind of rudder to
assist and direct their motions. That of the smaller
dragon flies {Agrion F.) is furnished with three long ver-
tical laminae, by moving which, as fish do their tails,
from side to side, the animal makes its way in the water ^.
That singular one, also, with a hooked head, figured by
Reaumur, has a single swimming lamina, or fin, shaped
like a fan, and placed in a vertical position under the
tail^

The whole circumference of the body m some coleopte-
rous larvae, — for instance, in that of the tortoise-beede
lately mentioned, — is surrounded with appendages like
rays. These are sometimes simple, rough with very
short spinous points f ; but I have a dipterous larva, in

a Reaum. v. 32. i. v./. 3—5. Latr. Gen. Crtist. ci Ins. iv. 249.

b De Geer ii. 1031. t. xl./. 13, U.kk.

c N. Diet. d'Hist. Nat. x, 430.

'1 De Geer ii. 697. t. xxi./. A,b.bb b.

" Reaum. v, t. vi.f. 7. n.

f Plate XVIII. Fig. 2.

STATES OF INSECTS.

155

which these radii themselves are beautifully pinnated by
a fringe of longish spines on each side. Reaumur has de-
scribed the grub of a beetle, the genus of which is uncer-
tain, and which feeds upon the larva of Aleyrodes Prole-
tella, whose body is margined on each side by eight tri-
angular fleshy mammular processes, terminating each in
a brisde, which give it a remarkable aspect ^ The cu-
rious scent-organs with which the larva of CJwysomela
Populi is fringed have been before fully described ; and
therefore I shall only mention them here

In the larvae of the lace-winged flies {Hemerobius), and
ant-lions ( Mi/rmeleon), the anus is furnished with a small
fleshy retractile cylinder, from which proceeds the silken
thread that forms the cocoon inclosing the pupa Pro-
vidence has many different ways of performing the same
operation. From the structure of the oral organs of
these animals, the silk could not conveniently be fur-
nished by the mouth ; the Allwise Creator has therefore
instructed and fitted them to render it by a spinneret at
the other extremity of the body.

The respiratory anal appendages of many Dipterous
larvae will be fully described in a subsequent Letter : I
shall therefore now only further observe upon this subject,
that although there is seldom any alteration in the form of
these appendages &c. in the same species, the caterpil-
lars of two moths {Cemra Vinula and Attacus Tau\ how-
ever, are exceptions. The former, when young, has two
hairy projecting ear-like protuberances, which it entirely
loses, as I have myself observed, before it assumes the
pupa; and the latter, in like manner, after its third

* Reaum. ii. t. xxv./. 20.

See above. Vol. II. p. 245 — .

Rcaum. ui. 384. vi. 366. t. xxxii./. 7, 8.

156

STATES OF INSECTS.

change of skin, is deprived of its bent thorn-like points
which attend it when young ^ It is remarkable that
these last larvae, when just excluded from the egg, are
also entirely destitute of these appendages ; they soon,
however, appear, from slight elevations which mark their
situation, and rapidly acquire their usual form''. Changes
of a similar kind, hitherto miobserved, may probably
take place in other species.

iii. Figure. I am next to consider the general figure or
shape of larvae. All of them, with but few exceptions S
agree in having a body more or less constricted at inter-
vals into a series of rings or segments ; usually in num-
ber, twelve ; often nearly equal in length, but sometimes
in this respect very dissimilar The general outhne or
shape of the body is extremely various : most frequently
it approaches to cylindrical, as in most of the caterpillars
of Lepidoptera, and of the Hymenopterous tribe of saw-
flies {Tenthredo L.). The next most common figure is
that more or less oblong or oval one, sometimes ap-
proaching to conical, found in many of the larv^ usually
called grubs; such as those of the weevU {Curculio L.) and

a Ros. iii. t. Ixviii./. 1. Meinecken Naturf. vi. 120.
b Ibid. xiii. 175.

c In the larva of Tenthredo Cerasi L., and some others, no traces
of segments are to be seen ; and in many coleopterous and dipterous
ones the folds of the skin prevent the segments from bemg distmctly
perceptible.

'1 Reaum. ii. 361 . In the larva of a small common moth often met
^^ith in houses {Aglossa pinguinalis), every segment is divided into two
parts,and underneath has two deep folds, by means of which these two
parts can separate to a certain point, or approach again, according to
circumstances. Thus Providence has enabled them to prevent their
spiracles from being stopped by the greasy substances on which they
often feed. iV. Diet. d'Hisl. Nat. I 208.

STATliS OF INSECTS.

157

of the Capricorn {Ceramhyx L.)? and other coleopterous
tribes ; of bees, and all Hymenopterous insects but the
saw-flies ; and also of a large number of flies {DijJtera).
In some the figure approaches to fusiform, as in most of
the moths of the Fabrician genus Lithosia. In others,
as in those of the water-beetles {Ih/tiscus, &c.), it ap-
proaches to an obovate shape, being widest towards the
head, and terminating in a point at the anus. In others,
again, it is linear; an example of which is that of Htaplnj-
linus. Some are convex, and others gibbous, above, and
flat underneath ; as thost of Silpha^ CJmjsomela and many
other beetles. Others are flat, both above and below,
and depressed like a leaf; a I'emarkable instance of which
has been before noticed ^. .?ome are vei*y long, as those
of most Lepidoptera ; others very short, as that of the
ant-lion [Myrmeleon). Many other peculiarities of form
in individuals might be instanced ; but a dry enumera-
tion of these would be of no great use to you. They can
only be advantageously learned by the study of good
figures, and by watching the actual metamoqihosis of the
singularly-formed larvae that you meet with.

Instead, therefore, of any further specification of indi-
vidual forms, I shall now endeavour to give you, as far
as my own knowledge of them and the information I can
collect from other sources will enable me, a laro-er and
more general view of the kinds of larvae ; for analytical
inquiries lose half their value and importance unless we
proceed to apply them syndietically, by forming, if pos-
sible, into groups the objects with which we are indivi-
dually acquainted.

Partial attempts at a synthetical arrangement with re-
* See abovej p. 1 10.

15^ STATES OF INSECTS.

gard to the Xnvvsi oi Lepidoptei-a and the saw-flies [Ten-
thredo L.) have been made both by Reaumur and De
Geer. M. Latreille also has recently given a Tableau
meikodique et general of articulated animals furnished
with jointed legs, considered in their first state ^ The
former of these is chiefly founded upon the number of
the prolegs, and the latter upon the metamorphosis, pro-
legs, habits, head, and parts of the mouth, without any
other notice of the configuration. Mr. Wm. MacLeay,
who, though young in years, is old in science and critical
acumen, has started a perfectly new hypothesis upon this
subject. In the progress of his inquiries into the natural
arrangement of animals, particularly of insects in the
Liimean sense, he has been the first to observe, that the
relation which organized objects bear to each other is of
two kinds ; one of real affinity, and the other only of ana-
logy, or resemblance. This important distinction, upon
which I shall enlarge in a future Letter, when I come to
treat of Systems of Entomology, he has applied, in a way
quite original, to larvae in general, but more particularly
to those of the Coleoptera order. For the basis of his
system he assumes a relation of analogy between the
larvcB of Insects that in the progress of their metamor-
phosis assume wings, and those that do not, which form
his class Ametabola, so that the prototypes of the former
shall be found amongst the latter ^ But though Mr.
MacLeay appears to consider the analogy between these
two as primaTy, he extends it m a seconda7y sense to the
C7-ustacea, at least in several instances Upon this oc-

» N Diet. d'Hist. Nat. xvii. 329.
y Hor. Entomolog. 285. 397— 432. 462-. &c.
mi. 399—401.

STATES OF INSECTS.

159

casiou he very judiciously remarks, that " in terming
larvae Chilognathiformes or Chilopodiformes, it is not
meant that they are ScolopendrcB or luli, or even near to
them in affinity ; but only that they are so constructed
that certain analogical circumstances attending them
strongly remind us of these Ametabola^ ." This remark
you will bear in mind while I am treating of this subject.
It should seem from another part of the same paragraph,
that the comparison which our learned Physiologist re-
commends, is between the young of the Ametahola and
the larvae of the corresponding groups of Coleoptera.
This must be understood to refer chiefly to the young of
tlie Chilopoda and Chilognatha^ since they approach
nearer to them m that state, having then only six legs ;
but the rest of the Ametahola should certainly be brought
to this comparison in their adult state : and even the two
former orders in tliat state more strongly resemble nume-
rous coleopterous larvae, than when they are young and
much shorter. I before called your attention to the re-
markable circumstance that contrasts very many larvae
of Hexapod insects that become winged in their perfect
state with adult Myriapoda : namely, that in one the pro-
gress to this state is by losing their prolegs and shorten-
ing their body ; while in the other, the reverse of this
takes place, numerous prolegs and additional segments
being gained before they arrive at maturity''. As the
multiplication of organs is a sign of imperfection, it may
be affirmed of the former of these tribes, that their pro-
gress is towards greater perfection; while that of the
other may be called a degradation. As larvae may be
regarded as a stepping-stone by which approach is made

" Ho>: Enfomolog. 423,

See above, p. 23.

160 STATES or INSECTS.

from the apterous to the wmged tribes of Insects, it seems
most consistent with general analogy that each should
connect with the other in that state m which the resem-
blance is greatest. Now the Myriapoda resemble larv^,
as we have just seen, most when in their adult state;
therefore the comparison shovdd be between larvae and
adult Myriajjoda.

Mr. MacLeay divides coleopterous larvae into five tribes
thus characterized : —

1. A carnivorous hexapod larva, mth an elongate linear
fattened body, having a large head armed mth two sharp
falciform mandibles, and furnished with six granular eyes
on each side. This kind he denominates Chilopodiform,
as having for its type in the Ametabola, Scolopendra L.
The examples he gives are Carabus and Dytiscus.

2. A herbivorous hexapod larva, with a long and al-
most cylindrical body, so fashioned that the posterior ex-
tremity being curved under the breast, the animal when at
rest necessarily lies like an lULUS on its side. This tribe
he denominates Chilognathiform, from lulus L. His ex-
amples are, the larvae of Petalocerous insects, as Scara-
bceus L., Lucanus L. &c.

3. An apod larva, having scarcely the rudiments of an-
tennce, but which is furnished instead of feet with fat feshy
tubercles i which, when continued along the back andbellyr
give the animal a facility of moving in whateva^ way it
may be placed. These he denominates Veiinform, from
certain of the Vermes intestina and MolUisca of Lmne
which he has associated with hi*s Annulosa \ His exam-
ples are, Curculio L. and Cerambyx L.

4. A hexapod and distinctly antenniferous larva, with a
n The Inteslinaux cavilaires of Cuvicr, and the Epkoaria of La-

marck. See Hor. Enfoniolog. 28G— .

STATES OF INSECTS.

161

subovate rather conical body, of 'which the second segment
is longer and of a different foiin from the others, so as to
give the appearance of a thorax. His denomination for
these is Ajiopluriform, from Pediculus L., forming Dr.
Leach's Anoplura. His examples are, Coccinella and
Chrysomela L.

5. A hexapod antenniferous larva of an oblong form^
having like thefm-mer vestiges of a thorax, besides two or
more articulated or inartiadated setaceous or corneous ap-
pendages to the last segment of the abdomen. This tribe
he calls Thysamiriform, fi-om Lepisma and Podura L.,
forming M. Latreille's order Thysanura. His example
is Meloe with a note of interrogation ».

The system here stated, of naming and characterizing
larvae from the resemblance and analogy, in many cases
very striking, that they bear to the apterous tribes, is a
very happy and original one, and does its author great
credit; yet I think m some mstances, as I shall soon
have occasion to point out to you, the application of it is
not so happy as the first idea. But this is always the
case when a new law of nature is discovered ; the proper
appUcation of it is gradually developed, and it does not
at all detract from the merit of the first discoverer, that
all the bearings of such law do not strike him as it were
intuitively.

» Ror. Entomolog. 422. comp. 463. Mr. xMacLeay's idea of the
larva of: Meloe is taken from the animal which Frisch, Goedart, and
De Geer imagined to be such; but upon this opinion there rest great
doubts. (See Kirby Mon. Ap. Angl. ii. 168, and Latreille Diet.
dHzst. Nat. XX. 109.) At p. 464 he gives also Mordella and many
Heteromem as having Thysanuriform lar^-ae. He thinks, that proba-
bly that of Clems is of the same description ; to which he suspects
that many of Latreille's Malacoderma likewise belong.

VOL, III. m

162

STATES OF INSECTS.

Having, however, got the vantage-ground aflordedby
this discovery of my friend, let us see if by standing upon
it we cannot get a tolerable generalization of the larvae
of all orders of insects that undergo a metamorphosis.
But first I must observe, that as in the perfect animals,
so in their larvae, the different groups are connected by
certain transition species, exhibiting characters common
to two or more of them ; and likewise that in many cases,
which you will see as we proceed, the analogy is as strong
or stronger between them and the Crustacea (and in a
few instances Arachnida, and even Mollusca) than the
Ametabola. My denominations, therefore, will be taken
from those tribes where the analogy appears to me the
most striking, and not from the Ametabola alone

I shall begin by drawing up for you a hst of the Pri-
mary forms that I seem to have observed, and then- cha-
racters; and then going through the orders, shall give
you the examples of each, with such observations upon
them as the case may require.

Primary Forms of Larvce.

APTERA.

ANOPLUaiFOEM:.

Thysanukiform.

Chilopodifoem.

Chilognathifokm

ARACHNIDA.
Araneidiform.

CRUSTACEA.
isopodiform.
Onisciform.
Idoteiform.
Amphipodiform.
Stomapodifohm.
Decapodiform.
Branchiopodifoum.

MOLLUSCA.
Limaciform.

ANNELIDA.
Vermiform.

Characters.

,. Anoplurif<mn. Carnivorous; hexapod ; antenniferous :
\L a shortish oblong depressed body, and d.stmct

STATES OF INSECTS.

163

thoracic shield. Example: Psocus, Coccinella^ most
Hemiptera ^.

2. Thysanuriform. Polyphagous; hexapod; antemiiferous:

body with segments of trunk distinctly marked; anus
often furnished with setae or mucro. Ex. Meloe^l
Thrips^ Aphis.

3. Chilopodiform. Carnivorous; subhexapod; antemiife-

rous body depressed, elongate, linear, witli falcate
acute mandibles, a distinct thoracic shield, and an
anal proleg. Ex. Ciciiidela ? Carabus L.

4. Chilognathiformi Herbivorous : body sUbcylindrical,

elcngate, linear; no thoracic shield; often many pro-
legs, sometimes a retractile one, and sometimes none.
— Ex. Elatei\ PetaloceTa, most Lepidoptet-d^ Ten-
thfcdo L.

5. Vermiform, Polyphagous ; apod ot hexapod : with

very short legs; antennae nearly obsolete; body
fleshy, plicate, with sides often plicato-papillose ;

" Plate XVIII. Fig. 1. as to the thoracic shield,
Mai^ 27, 183.2. This day, T. Allen, Esq. F.L.S. brought me in
a phial a vast number of the little insect which Goedart, Frisch, and
De Geer took for the larva of Meloe ProscarabcEus, which he found
on the leaves of Achillea Millefolium. These little animals were
coursing each other with wonderful velocity over the sides of the
phial. To assist them in their motions, they applied to the surface
of the glass the end of theu* abdomen, using it, like many lar\'ae of
Coleoptcra, as a seventh leg. This cuxurastance excited a suspicion
in the minds of both Mr. MacLeay sen., then visiting me, and my-
self, that after all they might be colcojAerous lai'vae. One, amongst
other circumstances, however, seemed to militate strongly against
this opinion ; namely, that in this inJfinite number none appeai-ed tot
differ in she.

Plate XVII. Fig. 13.

Ibid. Fig. 12. ; Plate XVl'lI. Fig. 4, 11, 13, &c,

M 2

164. STATES OF INSECTS.

no distinct thoracic shield. Ex. Curculio L., Cc-
ramhyx L., Musca L., and many other Dipteral

6. Araneidiform. Carnivorous; hexapod: body very

short; mandibles long, suctorious; animal lying m
wait for its prey in a pitfall it lias prepared; motion
retrogressive. Ex. Myrmeleon L. ^ Cicindela ?

7. Jsopodiform. Saprophagous; hexapod; antenniferous,

with longer antennae: body oblong; thoracic shield
distinct; anus styliferous or laminiferous. Ex.
Blatta L. Silpha L. ?

8. Onisciform. Herbivorous; polypod; antenniferous:

body short, oblong, depressed, margined. Ex. Enj-
cina, Lyccena, in the Lepidoptera, and some species
of Tenthredo L.

9. Idoteiform. Subcortical; hexapod; antennae obso-

lete: body much depressed, with the last segment
elongate, terminating in three or more mucros. Ex.
Larva from Brazil. Perfect insect at present un-
known.

I have placed this larva, which was described above ,
amongst crustaceous forms, because of the remarkable
resemblance which the last segment of the body bears to
that of the Idoteida^ ; but I do it with considerable hesi-
tation, since in other respects its type seems to be m tlie
Ametabola, In its want of antenna, very short legs, and
venlxal asperities, it resembles some of the Vermiform
larvse ; in its small head, distinct thoracic shield, and ob-
long shape, it approaches the Anopluriform ; and m its

„ WITT TTir .S 9 Pl ATE XIX. FiG. 8.

^ Plate XVIIl. ^^'^-'^'^■^^ •• ^ 17 is • Di- Geer ii. 1004.
c Fig. 3. Reaum. v. 97. t. xu./. 17, 18., Ue Ueer

t. xxviii./. 12.

See above, p. 110, 114,138,142.

STATES OF INSECTS.

165

very depressed body, but not at all in other respects,
the Chilopodiform. At any rate, it appears of a primary
Type.

10. Lcemodipodiform. Herbivorous; hexapod ; antenni-
ferous, with long antennae: body elongate, subcylin-
drical; second segment of the trunk the longest;
anterior pair of legs distant from the other two. Ex.
Phasma.

11. Amphipodiform. Herbivorous; hexapod; antenni-
ferous, with long antennas: body shortish, com-
pressed, saltatorious. Ex. Giyllus L. *

12. Stomapodiform. Carnivorous or saprophagous; hex-

apod; antenniferous, with long antennae: body elon-
gate, subdepressed, with raptorious hands, and ab-
domen wider than the trunk ; in aquatic species fur-
nished with lateral gills. Ex. Mantis, Ephemera ?
Sialis ?

13. Decapodiform. Carnivorous; hexapod; antenniferous:

body elongate, narrow, convex, compressed, taper-
ing towards the tail ; tail with natatorious laminae.
Ex. Dytisais L., Agrion F.

14;. Branchiopodiform. Carnivorous?; aquatic; apod;
antenniferous: head distinct: body transparent, flex-
ile, furnished with a respiratory tube just above the
tail. Ex. Cidex^.

15. Limaciform. Herbivorous; apod, or with very short
legs: body ovate or obovate, slimy. Ex. Apoda
Haw., Tenthredo Cerasi L.

» Plate XVIII. Fig. 7. " Plate XVIII. Fig. 5.
Plate XIX. Fig. 9.

IQQ STATES OF IXSEC'I'S.

The above are the principal forms that appear to me
Primary (though some doubt may rest upon the ninth
ftnd tenth); and probably others will hereafter be disco-
vered, since at present our knowledge of the larvae ot
most of the Orders is very limited. And now havmg given
you this generalization of them, as far as they are kno^vn
to me, I shall next, in a slight survey of those of the dif-
ferent orders, lay before you what I have further to ob-
serve upon this subject.

Coleoptera. Tlie Anoplurifom coleopterous larvae, ao-
cording to Mr. W. MacLeay's view of them, include
both those of Coccinella L„ Chrysomela L., and Cas-
sida L. ; but this appears to me to admit of further con-
sideration. With regard to the two former-those of
Coccinella are carnivorous, those of CImjsomela herbi-
vorous; the first is also usually more ^at and depressed.
As to the latter, Cassida % it seems to pie to belong to a
pecuhar type, distinguished not only by its radi.ted mar-
gin but by the remarkable deflected anal fork on which it
carries its excrement. At present I know no analogous
form amongst the apterous tribes ; I must therefore leave
this without a denomination. Perhaps the larva Htspa
or Alurnus, when known, will throw light upon this sub-
ject The larva of Endmmjchm agrees with that ot Loc-
cinellfi.

There are very few known larva that approach to a true
Thysanuriform type in this order: that most celebrated is
the one supposed to belong to Meloc; but the claim of this
to be so considered, is, as we have seen, rather dubious.
Should this point at last be satisfactorily ascertamed, it

=« Plate XVUI. Fig. 2,

STATES OF INSECTS.

167

will probably carry with it the whole tribe of vesicatory
beetles. But even this animal in its general structure is
anoplurijhrm : the only circumstance that gives it any ana-
logy to the Thysanura being its anal setae. Mr. William
MacLeuy is inclined to regard some of the larvae of the
Malacodeimi Latr., but which of them he does not state,
as probably belonging to the tribe in question ^. Those of
Lampyris and of Telephoinis, as described and figured by
De Geer ^, appear to me intermediate between the Ano-
pluriform and Chilopodifoi-m Types : they have no anal
setiform or styliform appendages, their mandibulae are
falcate, and their habits seem carnivorous. .

Examples of Chilopodifoim coleopterous larvae are
more numerous. Of this description are those of Gy-
rinus, Cicindela, Carabus, and Staphylinus. That of the
first, indeed, appears to be the most perfectly Scolopen"
driform of any yet known; yet the gills or respiratory
laminae, a pair of which issues from each abdominal seg-
ment, and two pair from the last prove that there is
no slight analogy between it, and indeed many other
aquatic larvae, and the Stomapoda amongst the Crustacea.
A remarkable instance of analogy with the Decapoda of
the same Class is presented by the larva of Dytiscus, &c.
which Mr. MacLeay considers as Chilopodiform^ but
which exhibits no other resemblance to Scolopendrce than

» Hor, Entomolog. 465. •> De Geer iv. 66, t. u.f. 5 — 8.

*■ Ibid. t. \m.f. 16 — 19. A very singular larva, which preys upon
that of Aleyrodcs pruletella Latr., if Reaiunur's figure be correct (ii.
t- XXV./. 18 — 20), is of a perfect Chilojjodiform type, the abdomi-
nal legs being represented by a tubercle crowned by a bristle : yet
even this, which turns to a minute beetle (Ibid./. 21), has some ten^
dency to the Anopluriform type.

168 STATES OF INSECTS.

in its predaceous habits and threatening aspect. Its
convex, compressed, tapering body, terminating in setae
or laminiE, is certainly much more like that of a shrimp
or a prawn ; to which the older Entomologists thought it
was akin », and after which they named it. As Mr. Mac-
Leay's object was, to take all his forms from the Ameta-
bola, perhaps these larvae will best fall in with his Chilo-
podiform type ; though in the general form of their body
they most represent a section {Lepisma L.) of the Thy-
sanura.

Chilognathiform forms are equally numerous in the
Coleoptera with the precedmg. The wire-worm, or larva
of Elates- Segetis, as to shape best represents the full-
grown Itdus^, and those of the Petalocei a [Scarabcexis L.,
Lucanus L.) the young one.

The most abundant of all forms in this order, is, I
think, the Vermiform^ upon which I have nothing further
to remark.

With regard to Crustaceous forms in Coleoptera, be-
sides the Decapodiform just noticed, I possess two speci-
mens of larvae of Silphidce which seem to exhibit a con-
siderable analogy with the Isopodous Cnistacea, one rather

" Squilla insectum a 2»sce paruvi differt." Mouffet, 319.

^ A remarkable difference obtains between the lai'va of the wire-
worm and that of Elater undulatus. In the former, the last segment
is longer than the preceding one, terminating in a small acute niucro
at the apex, with a deep cavity, perhaps a spiracle, on each side, at
the base. In the latter, this segment is shorter than the preceding
one, forming above a nearly circular plate; the margin of which is a
little elevated, and armed on each side with three teeth, and at the
apex with a pair of furcate j'ecurved horns, and without any basal
spiracle. De Geer iv. 156. t. v./. 25. I have a similar larva, but not
the same species.

STATES OF INSECTS.

169

convex and the other flatter, so as to give the idea of an
Armadillo and of an Oniscus.

Strepsiptera. Larva Vermifoim.

Dennaptera. Larva Thysanuriform. Type Podura or
Sminthnms.

Orthoptera. Mr. MacLeay considers the larvae of this
Order as primarily Thysanuriform % though he allows
the resemblance between them and Amphipoda to be par-
ticularly striking''. For my own part, their prototypes ap-
pear to me to be in the Crustacea, and their analogical re-
lations to the Thysanura much more distant. I trust this
will appear to you the reverse of dubious in a progress
through the Crustaceous Orders. I begin with the Iso-
poda. Take the larva of a Blatta, and place it between
a Lepisma, or Mackilis, and an Oniscus, or Porcellio ;
you will find that in shape and width, and the form of its
anal styles, it resembles the latter much more than it does
the former, with wliich it possesses scarcely any character
in common, except its multiarticulate antennae. It is re-
markable, that amongst the Blattida we meet with spe-
cies that represent both the Oniscidce and Armadillo or
Glomeris the latter being more convex than the former.
In their habits the Blattae certainly agree with Lepisma
and Dumeril, who thought the latter and Podura sub-
ject to a metamorphosis, imagined they were related

The Spectres of Stoll {Phasma F.) are so strikingly
analogous to another crustaceous tribe, the Lcsmodipoda,
particularly the genus Caprella, that Montagu gave one
species the Trivial name of Phasma". The jumping Am-

» Hor. Entomolog. 397. " Ibid. 39f). - Ibid. 438. Note *

Traite Element, ii. 35. n. 577.
" Trans. Linn. Soc. vii. 66. /. vi./. 3.

170 STATES OF INSFXTS.

phipudiform Crustacea are represented extremely well by
Giyllus L., and the Stomapodiform, particularly Squilla
Mantis, by Mantis. The resemblance in this last instance
is. so very striking, that it cannot escape the eye of the
least intelligent observer. Orthopterous msects may per-
haps one day be discovered analogous to the two other
crustaceous orders, the Decapods and Branchiopods ; but
at present I know of none of that description.

Hemijotera. The larvae of this order, which in general
resemble the perfect insect, except that they have no
wings, seem most commonly to belong to the Anopluri-
form type*; but the Aphides, Chermes, and Tlirips may,
I think, be regarded as more analogous to the genera
Podura and Sminthurus in the Thysaniira ^ I have some
suspicion that the Nepidce, Naucoris, and the remipedes,
Notonecta, Sigara, &c. may find their prototypes amongst
the Crustacea ; but my confined knowledge of the latter
does not enable me to point to any individual genera or
tribes that they may be presumed to represent.

Neuroptera. As the kinds of larvae of the different tribes
composing this order, as it now stands, are very various,
it is to be expected that the analogical forms they repre-
sent are equally so. The Libellulina MacLeay (whose
metamorphosis that gentleman has denominated sub-
semicomplete, a term warranted by their losing in their
perfect state the mask before described in their oral
organs, particularly by their galeate maxilla and distmct
ligula S have some relation to the Orthoptera, the pi'oto-
types of whose larvae we have found amongst the Crus-

« Compare De Geer iii. t. xi./. 3. and /. xvii./. 14. &c.

h Ibid. t. If. 4, 9. t. ilf. 1 5. /. ix./. 4. See above, p. 13o-.

" Compare Plate VI. Fig. 6. with Fig. 1 2 e, d, d.

STATES OK INSECTS. HI

tacea : probably, therefore, those of the tribe in question
lurk m that class; a suspicion that receives strong con-
firmation from the larva of Agrio7i % which in its taper-
ing body and anal natatorious lamina? represents a shrimp.
Thelar'vse of that very peculiar and distinct tribe, the Ephe-
merina, appear' to be intermediate between the Stomapo-
diform and Thysanurifmin types. Their natatory respira-
tory abdominal laminae seem copied fi'om the former, and
their anal diverging setje from the latter ^ The Mijrme-
leonina, as well in their general form as in their inotions
and habits, present a most singular analogy with the tribe
of spiders, as does also in some respect that of Cicindela.
With regard to Panoipa, which Mr. MacLeay remarks
is related to Myrmeleon^, and is a most ferocious insect
as its larva has not yet been discovered, nothing certain
respecting its analogical form can be asserted; but should
it, like the male fly, represent the scorpion, both orders
of Arachnida will have their representatives in the class
we are considering. The Cojydalma, as far as the larva
of Hemerohius instructs us, is CMlopodiform^ but with a
tendency to the Araneidiform Type, The Ametahola
also furnish the prototype of the next tribe, the Termi-
tina, which, as is evident both from Psocus and Tei-mes,
are perfectly Anopluriform. The Sialina, or Plicipennes
of Latreille, excluding Trichoptera Kirby, appear to me
to be intermediate between the Chilopodiform and Stoma-
podiforvi Types, and not without some relation to the
Thysanurifm m. Their pediform, jointed, respiratory ab-
dommal appendages, their head and falcate mandibles,
seem copied from the first tribe. The same appendages

» Dc Gcer ii. t. \x\.f. 4, 5. Swanim. Bih/. Nat. 1. xiii./. 1.

Hot: Enlomohg. 438. Sec above, Voi,. II. p.

172 STATES OF INSECTS.

considered as organs of respiration, and their taper forks,
are moulded upon the plan of the Stomapodiform Crus-
tacea, and the long seta which terminates the abdomen is
upon the Thysanuriform plan ^.

TricJioptera. The larvae of this order appear also to
be constructed upon a double plan. The respiratory
threads observable in both the upper and under sides of
the abdomen connect it with the Stomapoda, and its cy-
lindrical elongate body with Chilognathiform types in the
Lepidoptera ^.

Lepidoptera. The great majority of larvae in this or-
der are Chilognathiform, but there are exceptions to this
remark. Those of the Geometry recede from this type,
both in their motions and the distance and number of
their legs. In both these respects they represent the Lce-
modipoda in the Crustacea <=. Other caterpillars are Onis-
ciform; and a third sort seem to leave the Anmdose ty^e,
and imitate that of the Molhisca, and on^ is figured by
Madame Merian'^ which appears to tend even to the
Chilopodiform type.

Hymenopte7-a. In this order the larvae of the saw-flies,
Tenthredo'L., are in general Chilognathiform, though some
are Onisciform, others Limaciform, and those Lyda F.
{Cephaleia Jur.) and Sirex'^ have a Vermiform tendency,

» De Geer ii. t. xxiii. /. 9—14. Comp. Reaum. iv. t. xv.
/' 1 2

b'oe Geer ii. t. xiv./. 7. &c. The caterpiUai- of P. G. Scratiotata
L like those of Fhryganece, has these respiratory threads. Ibid. ^.
t 'xxxvii./. 3—6, De Geer has described the larva of a Phryganea L.
which is' without any respiratory threads, ii. 569. U xv./- 10.

c Hor. Entomolog. 401. Montagu in Linn. Trans, mi. bj.

" Ins. Surinam, t. xxviii. Compare Ibid. t. xix. right-hand figure.

« Plate XVIII. Fig. 10.

... </// /////>« ifcud t^^KKi*'.

tli*: AunuUm. 'i'JUu*, tLt JU vii vi" UlrUi^uiu Cfux^
oUmn, y«t iii *iU*M^t aJJ ttuti i Wve stated U*^;-i ^. - tJj«t

JkiiMi l-ejicwbliwwx; tlj^ <X>ukl iJKX tLw; /fcbult <4 tt'Jutat iti
citJJiid ^iMii i: cUaiK;*:; aiid Mi . MjaA:iA^y, by fkxt jX)Uituig
<>ut tiiii> piwi <^ tlw; AJJ/-wi4>fc OtitWi> aud by luyiiii^ <l</»vii
Uu: <i(>cU'UM; u/u/lfjgu'i iu j/^iuw.ra\} afe diw ' ' -jbtd liv^i
ojfi/iilm In tiiAt iiJxUiia-l kiu^doui, Ixub Ju' tJU^ U>-

j/i/^id«j, lii*U. would i*?iidiii auU tUow; tJit wLsd^tu

Ui»i wmJ vcj^ctai^k: ciiAitk»ii l'uJ ijju>lj Ub 5 by ajttii iuiiig niotit
abbwdly, uwd uud*;; tju*; ^K/trt- btuitiiykig bUudii«iSti
iijj/id^ tbM tij* crmtmen wtcx*t iu n juu^miAer tUik owu ere-
aU/f s, dfcfcir wajut* uud<ir l<XiaJ cijctuutftiUKXJb btiiiiuitttmg
tWj> U> «iftb/U tijuit iju a ioiig wui m; <^ yey/ti ^odu<;<5d
aJJ {h^c diifcjrwjit ib/iub iuid oi•g^^J0WJltk>iJJ^ tlu*t a/<^ xkm*' U>
k»uu>d jji our ^->i>«;, 'l'ii<; afliiiiti** aud clobe coaiiexioii
l>*siiig*i witU <->tiiW, w tUat tin; iiiiusut Ironi io**' W
higli it, uMjudiy by tlw; ifiowt g<;udtU; gradaiioiib, ib the ck-

' )S»a«iiiii. /yi/y/. N'4. i. xxxi:- / n. XIX. Fi' K:!

174- STATES OF INSECTS.

cumstance on which they build this strange and impious
theory. But the fact, that certain animals of one tribe
were created with a view to certain animals of another,
so as to present a strildng aspect of correspondence, pa-
rallel almost with that of type and antitype, without any
real affinity or approximation;— this triumphantly proves
a Power above and without them, who has associated
them not only in a complex chain of affinities, but has
caused them to represent and figure each other, even
when evidently far removed, so as to give a mutual cor-
respondence and harmony to the whole, which could be
produced only by a Bemg infinite in power and wisdom,
who made all things after a general preconceived plan
and system.

iv. We are now to consider the clothing with which
larvae are furnished. Many are quite naked, and smooth
or rough only with granular elevations or tubercles or-
derly arranged; but a very considerable number, espe-
cially of the Lepidoptera order, are clothed with han- or
bristles of different kinds, in greater or less abundance,
and arranged in different modes; and a proportion still
smaller have theii' skin beset with spines or a mixture of
spiiies and hairs. Lyonnet found tliat the hairs of the
caterpillar of the great goat-moth ( Cosms ligniperda) were
hollow, though not to the apex : probably this is the case
with those of other larvae, as well as with then- spmes.
In this instance they were set, he observes,- in a corneous
ring, or very short cyhnder, elevated a little above the
skin' The hair passes through this ring, and appears to
be rooted in a soft integument, which clothes the skm
within, and upon which the nerves form a reticular tissue.

STATES OF INSECTS.

175

some of which he thinks he has even seen enter the i-oot
of the hairs, which perliaps are organs of touch

Of the pilose larvas, some, like most of those of the
smaller moths [GeomeLra, Tortrix, Pyralis, &c.), have
merely a few scattered short hairs, scarcely perceptible ex-
cept through a lens : others ( Odenesis jiotafon'a, Lasiocam-'
pa liubi) are covered with down more or less thick : iu
others [Eriogastcr lanestris^ Lasiocavipa Neustria) the
hair is slenderer, and more hke wool; the body of two spe-
cies which I purchased from the collection of Mr. Fran-
cillon is covered with woolly hairs, so long as to give
them the appearance of a shock-dog; and Madam Merian
has figured a similar one, which she coidd not bring to the
perfect state Tiie hairs of many Boinhi/ciche, known
commonly by the name of hah-y caterpillars, as Arctia er--
minea, &c. are stiffer, resembling bristles ; sometimes, as^
in Arctia chryswhea, mixed with shorter ones. The
hairs either spring immediately from the skin [Noctua
Aceris, lepoi'ina), or, as is more general, proceed only
from certain tubercular elevations, usually subhemisphe-
rical, but sometimes conical ; of which a number varying
from four to twelve are found on each segment of diffe-
rent species. They seem to issue fi-om these tubercles,
as little diverging streams from the rose of a watering-pot.
In both cases, they form a coating usually so dense as
to conceal the body, but sometimes more thinly set, and
admitting the skin to be seen more or less between then).
In a caterpillar of the beautiful Arctia oculaiia, the hairs
are set upon tubercles alternately nearer the anterior and
posterior margin of each segment, so as to form a dense

» Lyonnet G9—

Surinam, t. Ivii. right-liand figure.

1 76 STATES OF INSECTS.

band, the rest being naked ; and in the lovely green and
black one of Saturnia Pavonia, each tubercle bears but
six hairs, diverging like a star, the central one being the
longest and capitate, so that the chief part of the body
appears naked. This diverging position of the hairs is
most connnon in the thick-clothed larvae also, but many
have them placed dilFerently : thus, in those of Callimor-
pha Caja audArctia mllica^ they are all directed towards
the tail, like the quills of a porcupine : in some others
the anterior ones point towards the head: in that of
Eriogastei^ Qiiercus half of the tuft of hairs of each tu-
bercle is directed downwards, the other half upwards :
m that of Arctia Salicis all the hairs point downwards,
so tliat the belly is thickly covered, while the back is
bare. Another variation is, that the hairs of half the
tubercle are sometimes very long, while those of the
other half are very short, and even of a different colour ^.
In the larva of Tussuck moths {Laria pudibunda, fasce-
Una, &c.) the hairs are collected into tufts of a singular
appearance, those on the intermediate segments of the
back being quite level at the top, so as to resemble so
many brushes; while those on the first and last segments
are longer, and composed of feathered hairs converging
to a point at their extremity, Hke a common camel-haii-
pencil This last mode of arrangement prevails also in
the larva of Nodua Aceris ; but in this the pencils are
shorter, exactly wedge-shaped, and distinguished by an-
other particularity, that of springing directly fi'om the

a Sepp iv. t. W.f. 3. t. \vlf.3, 3.
b N. Did. d'Hist. Nat. vi. 254.

>• Plate XIX. Fig. 6. One of these larvae was taken at Mel-
ville Island. See Parry's Voyage, Appendix No. x. 37.

STATES OF INSECTS.

177

skin, and not from a tubercle. This is also the case with
the large caterpillars of Odenesis Rotatoria, which has a
double row of short bundles of black hairs on the back,
intermixed with larger ones : at each end of the body is
a pencil of converging hairs, and the sides are spotted
with bundles of white ones, which with longer tawny
ones are bent downwards, so as to cover the sides of the
creature Some have the anterior aigrettes disposed like
the arms of a cross, of which the body of the cateipillar
is the stem But not only is there considerable variety
in the general arranirement of the hairs that clothe our
little larva;, the hairs themselves differ much in their kind
and structure, of which I will now, before I proceed to
consider spines, give you some account. Several of them
are feathered like the plumes of a bird : tliis is the case
with those of Moi-pho Idojneneiis, on each segment of the
body of which are three blue tubercles, like so many little
tui quois beads, from each of which proceeds a long black
plume Other hairs terminate in a club ; those of the
larva of Noctua Alni, a specimen of which I possess taken
in England, are flat and incrassated at the apex, some-
thing like the antennae of some Sj}hingid(e^ Mad. Merian
has figured the caterpillar of another moth which feeds
upon the Papaw-tree {Ca)-icaPapa7/a) whh similar hairs'*.
But the most remarkable larva for the shape of its hairs
is that of Anlhrenus Musceorum, the little pest of our ca-

' Sepp. iv. t. viii. /. 4. Some species have three, others four,
and others even five of these brushes. N. Diet. cTIIist. Nat. vi,
255.

Ibid. Merian Enic: xxxiv. upper left hand figure.
" Merian Ins. Surinam, t. Ix.
' Ibid. t. xl.

VOL. HI.

178 STATES Ol' INSECTS.

binets, which I noticed in a former letter \ All the hairs
of its body are rough with minute points ; but those of
six diverging long tufts or aigrettes, laid obliquely on
the anal extremity of the body, which the animal when
alarmed erects as a porcupine does its (luills, are of a
most singular structure: every hair is composed of a se-
ries of little conical pieces, placed end to end, the pomt
of which is directed towards the origin of each hair, which
is terminated at the other extremity by a long and large
conical mass, resembling somewhat the head of a pike^
Besides the one lately mentioned, other caterpiUars
are rendered striking by the brilliant colour of the tuber-
cles from which their hairs emerge. A remarkable m-
stance of this is the thick large caterpillar of a Bombyx,
which feeds upon the Psidium pt/riferwn, or white Guava,
figured by Madame Merian. This caterpillar, which is
white, with transverse black stripes, and which has two
singular long converging curved bunches of hairs near
the tail, is splendidly adorned on each side with fifty red
tubercles, shining like coral, from which proceed six or
seven long diverging hairs. Leeuwenhoeck took these
tubercles for eyes ^ Another figured by the same ady,
who mistakes it, with her usual inaccuracy, for the larva
o^aLvg^ns R, and which seems by her description to
be between the onisciform and limaciform types, has the
apparently fleshy mamillae that project fi-om its sides and
back crowned with little hairy red globes, which give the
animal a most singular and unique appearance^. Hav-
ing thus described some of the principal modes m which

» See above, Vol. I. p. 238.

h De Geer iv. 207- t. viii./. 4-6.

c Sur. t. xix. right hand caterpillar. If^d. xli.

STATJiJi Of INSECTS.

179

the All-wise Creator has decked and defended these
creatures with hairs, I shall next give you a shoit ac-
count of the spines with which he has armed others.
The spinous larvae are principally lepidoptermis, and more
particularly conspicuous in some tribes of the genus Pa-
pilio L., though some saw-flies and Diptera are also di-
stinguished by them. Vanessa lo^, Atalanta and Urtica,
Argynnis Paphia, Urania Leilus, and many other But-
terflies, &c. are clothed with long sharp points, which
claim the denomination of spines, rather than that of
hairs or bristles ; being horny and hard, and so stiff" at
the point as readily to pierce the skin. Those of the last-
mentioned species, Madame Merian says, are as stiff" as
iron-wire''. 'They are sometimes entirely simple, and
look like spikes rather than spines, as in the caterpillar
of Nymphalis Amphinome and Mo7pho Menelaus ; but
ordinai-ily they are beset with hairs, or more commonly
with shorter spines, which often give them the appearance
of plumes, as m Urania Leilus just mentioned: sometimes
these lateral spines are so long as to have the appear-
ance of a branch of a tree; this is strikingly the case with
a small caterpillar which Captain Hancock brought from
Brazil ; its body is so thickly planted with spines of this
description, that it absolutely wears the appearance of
a forest or thicket in miniature. A singular cuxum-
stance attends the spines of this species : in many cases
a smaller and very slender hair-like spine issues from
them, resembling a sting ; and this accounts for an ob-
servation of Abbott's, that many American caterpillars
sting like a nettle, raising little white blisters on the skin

» Plate XVIII. Fig. 13.
Ins. Stir. /. xxix. • Ibid. t. vii. liii.

180 STATES OF INSECTS.

when accidentally or slightly touched \ Lewin has de-
scribed the caterpillar of a moth found in New Holland,
which he names Bomhyx mlnerans, that, like these Ame-
ricans, has also the power of wounding, but in a different
way. It darts out, he says, when alarmed by the ap-
proach of any thing, from as many knobs or protube-
rances in its back eight bunches of little stings, with
which it inflicts a very painful and venomous wound \
The caterpillar of Papilio Protesilaus F., if Madame Me-
rian's account and figure of it are correct, has its body
armed with hairy spines, the extreme point of which is
surmoimted by a star-shaped appendage \ Those of a
few saw-flies {Tenthredo Pruni L.), and another figured
by Reaumur ^ are covered with a little forest of spines
without lateral branches, but divided into a fork at the
apex. Some spines are merely rough, with very short
points, as those round the head, which give so terrific an
appearance to the caterpillar of the Bombyx regalis, of
some proceedings of which I gave you an account in one
of my former letters ^

I must now say something upon the arrangement of
these spines. Though in a few instances so thickly set
as entirely to conceal the body of the animal, as m the
case of the Brazil one lately mentioned, yet generally
speaking, even when they are most numerous, they per-
mit the skin to be distinctly seen. Their arrangement
is various, though always orderly: in the majority they

■ ^ Smith's AbhoWs Ins. of Gcorg. Pref. vi.
b Prodromtis Entomology.

c Ins. Sur. t. xliii. The figure represents only the two spines near
the head as thus circumstanced.

d Reaum. V. /. xii./. 8, 14. Plate XVIII. Fic. 11.

« See above, Vol. II. p. 338. This, with B. impemUma, &c. m the
modern system, should form a genus.

STATES OF INSECTS.

181

are planted singly, but in so^ne caterpillars in bundles.
I In that of Saturnia lo^ on each segment there are six bun-
illes of longish, quill-shaped, sharp, slender, diverging
-pines, which also appear to sheath aculei. Madame
Merian has figured this larva, or one very near it, as the
<^n-ub of a Euglossa with which, though she affirms she
t raced it to the fly, it can have no connection. With re-
gaixl to number, some larvae have only four spines on
each segment ; others five, others again six, and others

< seven, or even eight : they are planted on the sides and
I back only, never on the belly. The}' are often more nu-
rmerous on the intermediate than on the anterior and
j posterior segments ; but sometimes the reverse of this
t takes place ; in that of Attacus ErythrincB only the liead
: and tail are armed with spines, the rest of the body being
\ without any''; and in that of Morpho Teucer there is
c only a single spine on tlie four intermediate segments ^.

They are usually all nearly of equal length ; but in some
i cases those of the head and tail are much longer than
[ the rest, and remarkably so in the caterpillar of Urania
J Leilus, also beautifully plumose, and gracefully waved

Those in the second and third segments are much longer
t than any of the rest in that of Bomhyx regalis ; which
(circumstance gives it the terrific appearance lately al-
1 luded to. In the family to which Argynnis Paphia be-
1 longs, the larva is adorned with two on the back of the
I first segment twice as long as the rest, and resembling
j at first sight two antennae.

The spmes, as well as the hairs of the new skin, are

< concealed under the old one, and not incased in its spines;

» Ins. Sur. t. xlviii. riglit liaml figure. ^ Ibid. I. xi.

' /i''/. t. xxiii. d JliJ^ f ^xi^.

182 STATES OF INSECTS.

but Bonnet ascertained, that if cut off very closely, the
larva sometimes died in consequence, whilst no such re-
sult followed a similar operation on hairy larvae. We
learn from Reaumur S that some spinous larvae of saw-
flies ( Tenthredo L.) lose their spines at the last change of
their skin; and from Madame Merian, that that of
cus Erythrina before mentioned loses also at the same
period the six tremendous black spikes that arm its black
and yellow larvae. The grubs of ants that are destined
to pass the winter in the larva state are hairy, but are not
so in summer The spines found in the grubs of some
gad-flies {CEstrus L.) are of a different kind from those
above described, being very minute triangular flat plates,
arranged in different and contrary directions S and serv-
ing the insect merely to change its place and fix itself

Two other kinds of clothing, if so they may be called,
neither coming under the description of hairs nor spines,
are found in some other larvae, not only amongst theXe-
pidoptera, but also in some of the other orders. Nt/jh-
phalis Populi and others of the same family have larvae
furnished on the back of each segment with cylmdrico-
conical processes of a fleshy substance, obtuse at the apex
and surrounded with capitate hairs. In that of N. Sy-
billa, which has on each segment two fleshy protube-
rances, they are bifurcate or trifurcate, and also encir-
cled at the base with a haiiy tuft Others, as those of
Melitaa Artemis, Cynthia, &c. have each segment beset
on the back with from seven to nine fleshy, pubescent,
wedge-shaped protuberances ; two larger ones projecting

» Reaum v. 95. " ^^^^ Fourmis. 7^.

e Seeabove^VoT,.II.p.276-. Reaum. v. 72. /• ix-/- 2-4;
<: Ros.

STATES OF INSECTS.

188

over the head. Under this head, too, may be noticed,
the ghitinous secretion which clothes the grub of Cionus
Scrophiilari(Ei a Httle weevil ; and of Tenthredo Cerasi L»
a saw-fly, and that waxy or powdery substance which
transpires through the skm of the larvae of several ApJii-
des, Che7inesy Cocci, Hylotoma avata F., &c. The Aphis,
whose extensive ravages of our apple-trees {A. lanata)
were before described to you is covered and quite con-
cealed by this kind of substance, so that the crevices in
the bark which they inhabit look as if they were filled,
not with animals, but with cotton. The insect, also,
that forms those curious gaUs produced upon the spruce
fir, and which imitate its cones {Chermes Abietis L., Aphis
De Geer) secretes a similar substance. In these and
other cases of the same kind, this matter seems to be, if
I may so speak, wu-e-drawn tlirough numerous pores in
certain oval plates m the skin, more depressed than the
rest of the back, arranged regularly upon the segments,
and exhibiting minute txiberosities. When young, these
animals have more of this secretion than when more ad-
vanced: it then hangs from their anal extretnity in
locks ''.

But the insects most remarkable for a covering of this
nature are those Coccidce of which Bosc has made a ge-
nus imder the name of Dorthesia. De Geer is the first
author that notices them, and has given a description
and figure of one species under the name of Coccus floc-

^ See above, Vol. I. p. 29, 198—.
De Geer iii. 111. Comp. 121. It would be as well to adopt the
French word fiocon, instead of locki or flocks, which strictly mean
very diflfferent thingi.

184

STAGES or INSECTS.

costis It was discovered by Modeer ujDon some sei-e
fir-leaves in a thick bed of moss. Panzer has figured n
second found upon Geranium sanguineum, which from
the figure appears distinct from De Geer's, under the
name of Coccus duhius ^. Fabricius regards this as syno-
nymous with the Dorthesia characias of Bosc, inhabiting
Eujohorbia characias in South^ Europe OHvier found
a species upon the bramble I once took one, which
appears to differ in some respects from the preceding spe-
cies, upon Melampyrum mstatim^ and our indefatigable
fi-iend Mr. Sheppard has sent me another, on what plant
found I do not remember, which does not agree with any
that I have mentioned. The body of the animals of this
genus is covered by a number of cottony or waxy laminas
which partly cover each other, and are arranged usually
in a triple series : in De Geer's figure the series appears
quadruple, the lateral ones being placed obliquely. The
anterior one in my specimen covered the head, and they
are all canaliculate. Above the anus are four diverging
ones : the whole are of the most dazzling whiteness.
When these laminae are removed, the body appears di-
vided into segments.

With respect to those larvae which imitate slugs by the
viscid covering that besmears them and issues from their
pores, we learn from Professor Peck that this exudation
takes place as soon as they are hatched ; that the animal
retains its humidity although exposed to the fiercest heat
of the sun, and that at the last moult the skin becomes

" vii. 604. /. xliv. /. 2G.
<• Si/sf. Rhipig. 311.29.

^ Fju Germ. Init. xxxvi. 21.
N. Did. d'Hisf. Nat. ix. 554.

STATES OF INSECTS.

185

quite clemi, and free from all viscidity^ It is probable
that the other limaciform larvae are similarly circum-
stanced. Madame Merian has figured an onisciform one,
the legs of which, she says, are covered with a viscid skin :
this produced a Noclua. Those of Papilio Atic/iises also
are slimy, and adhere to each other ^.

v. Amongst other qualities which attach to larvae, we
must not omit to say something concerning their Colour,
For though those which live in darkness, in the earth,
in wood, in fruits, &c. are, with few exceptions of an
uniform whitish colour, yet such as are exposed to the
influence of the light are usually adorned with a vast va-
riety of tints, sometimes the most vivid that can be ima-
gined. That the white colour of the former may be at-
tributed to the absence of light is proved by an experi-
ment of M. Dorthes, who having forced some to live un-
der glasses, exposed to the light, found that they gradu-
ally became brown To attempt any classification of
coloui'ed larvae would be in vain, since they are tinned
with almost every possible shade that can be conceived,
of many of which it would be difficult to find examples
elsewhere; and infinitely diversified as to the arrangement
and figure of their multiform markings and spots. A few
general remarks, therefore, are all that you will expect
on this head. Many are of one uniform colour ; while a
variety of tints, very different, and very vivid and distinct,
ornament others. Sometimes they are distributed in

" Natural History of the Slug-worm, 7.

Ins. Surimnt. t. xv. Kvi\.
'■ The larva? of Carnhm L. form one, being generall}- black.

Aivinles de Chhme ii.

186 STATES OF INSECTS.

longitudinal rays or bands, at others in transverse ones.
Sometimes they are waved or spotted, regularly or irre-
gularly ; at others they are sprinkled in dots, or minute
streaks, in every possible way. Various larvae are of the
colour of the plant on which they feed, whence they are
with difficulty discovered by their enemies. Thus, a large
proportion of Lepidoptera are green of different shades,
sometimes beautifully contrasted with black bands ; a cir-
cumstance which renders the caterpillars of two of our
finest insects of this order as lovely as the fly : I mean
that of Papilio Machaon and Saturnia Pavonia. Very
frequently the larvae of quite different species resemble
each other so exactly, in colour as well as shape, as
scarcely to be distinguishable: this sometimes takes
place even where they belong to different genera, as in
those of Bomhyx versicolor a moth, and Smeri7ithus Po-
puU a hawk-moth. And it sometimes happens, very for-
tunately for distinguishing allied species, that where the
perfect insects very nearly resemble each other, the lar-
vae are altogether dissimilar. Thus, the female oi Pieris
Rapce is so much like the same sex of Pieris Brassiere,
that it might be taken for a variety of it, did not the
green caterpillar of the one, and the spotted one of the
other, evince the complete distinction of these butterflies.
Nodua Lactuca, N. umhratica, and several other species
of the same tribe, which includes N. Ahsmthii, Vei-hasci,
Chamomillcc, Abrotmii, are so extremely alike, that the
most practised eye can scarcely discover a shade of dif-
ference between them, though their larvae in colour and
markings are constantly distinct\ The markmgs of

» IVicii. Verx. 219.

STATES OF INSECTS. 187

species belonging to the same family are usually diffe-
rent; but in some cases the latter maybe prejudged from
the former. The larvae of many of the genus Sphinx L.,
for example, have their sides marked by oblique streaks
runnino- from the back in a direction towards the head ;
and by this last circumstance they are distinguished from
those of Bombyx veisicolor, Attaais Tau^ and others of
the same tribe, which have also lateral oblique striae, but
runnino- from the back towai'ds the tail ^ The colours
of individual larvae of the same species are usually alike,
but in Sphinx Elpenor and some others they vary exceed-
ingly. Many, like those of Lasiocampa Rtibi, Saturnia
viinm\ &c., are of one colour when first disclosed, and
assume others quite different in riper age. Just previ-
ously to changing their skin, the tints of most larvae be-
come as dull and obscure, as they are fresh and vivid when
the change has fully taken place ; and in some instances
the new skin is quite differently marked from the old one.
This is remarkably the case with the last skin of some of
the larvae of the genus Tenthredo L., which is entirely
different from all the preceding ones. As people when
they advance far in years usually become more simple in
their dress than when they were young, so tlie larvae in
question change an agreeably variegated skin for one of
a uniform and less brilliant colour ^. Madame Merian
has observed with respect to Attaais ILrythrince, that its
caterpillar is at first yellowish, with nine black striae
on each side: when arrived at one third of its size,
they become orange ; the striae are obliterated, and in
their place a round black spot appears on each of the

* Wien, Verz. 4.

Reaum. v. 92.

188 STATES OF INSECTS.^

eight intermediate segments ^ Mr. Sheppard has re-
marked to me, that the skin of that of Sphinx Ligustri,
after being under ground four days, was changed from a
vivid green to a dull red. Very rarely, however, it be-
comes of a more brilliant hue just before entering the
pupa state : thus, that of another hawk-moth [Smeyinthm
Tilice) changes to a bright violet ; and the yellow hairs
of that of Laria pudibunda then become of a lovely rose
colour. And here I may observe, that the hairs and
spines also, of larvae, vary greaUy in colour. They are to
be met with brown, black, red, yellow, violet, white, &c.
De Geer found, that hi the larva of Cimhex ?iite?is the
two sides of the body were of a different colour, the
left being of a deep green, whilst the right side and the
rest of the body were paler but as he saw only a single
individual, this was probably an accidental circumstance.
Though the caterpillars, as I lately said, of one of the
most beautiful butterflies and moths that inhabit Britain
contend with the perfect msect in loveliness, yet in gene-
ral no judgement can be formed of the beauty of the fu-
ture fly from the colour of the larva; and the young Au-
relian must not flatter himself always with the hope, be-
cause the caterpillar excites admiration by its colours and
their arrangement, that the butterfly or moth it is to pro-
duce will do the same ; nor ought he to despise and over-
look a sombre or plain-coloured hidividual of the former,
under the idea that it will produce one equally plain of
the latter, for it often happens that the splendid cater-
pillar gives a plain butterfly or moth, and vice versa.
De Geer, however, gives us two instances of conformity

^ Ins. Siir'nutm, t. xi.

ii. 1017-

STATES OF INSECTS.

189

between the colours of the caterpillar and those of the
future moth; the one is that of the common currant-
moth {Phalccna G. grossiilariata L.), the caterpillar of
which is white, ornamented with several black spots va-
r^'ing in size. At the two extremities it is yellowish, with
a longitudinal ray of the same colour on each side, the
head and legs being black. These colours are all to be
found in the fly, the ground of its wings being white or-
namented with many black spots of different sizes. Its
upper wings are traversed by a yellowish band; and
towards their base is a spot of the same colour. Its body
is yellowish, with black spots ; but the head and legs are
black ^. The other is that of a green caterpillar, which
gives a green moth, figured by Reaumur [Pyralis prasi-
naria Fab.)*^ Sometimes, also, the sex of the future per-
fect insect may be predicted from the colour it exhibits in
its first state : thus, the brown caterpillars of Noctua Pro-
nuba produce males, and the green ones females The
sexes, also, of N. cxoleta and Persicarice differ in that
state.

vi. To the full account of the Food of insects given in
a former letter which had reference chiefly to their
larva state, it is only necessary in this place to add a few
particulars not there noticed. Many larvae when first
excluded, as those of Pieris Cratcegi^ &c. devour the
shells of the eggs from which they have proceeded ^; and

» De Geer i. 57, ^ Ibid. . 58. Reaum. i. L xxxix./. 13, 14.
De Geer ii. 400. See above. Vol. I. Lette7's xii. xiii.

" Bonnet (ii. 18) mentions, that the young larvae of a butterfly
{Pieris Cratcegi), after devouring the exuviae of the eggs from which
they were hatched, gnawed those which were ppt so : not, however.

190 STATES OI- INSECTS.

Others {Cerura Vinida, Sphinx Euphorhice, Noctua Ver-
basci), though their usual food is of a vegetable nature,
eat with great apparent satisfaction the skins which they
cast from time to time, not leaving even the horny legs.
This strange repast seems even a stimulating dainty,
which speedily restores them to vigour, after the painful
operation by which they are supplied with it. Under
this head it will not be out of place to mention, that some
larvee of insects, which feed only on the juices of animals,
or the nectar and ambrosia of flowers, have no anal pas-
sage, and of course no feces. This is said to be the case
wi°h the grubs of bees, wasps, the larvje of Myrmeleoji, &c.»

vii. You will require no stimulus to induce you to at-
tend to the subject I am next going to enter upon,— the
Moulting, namely, of Larva; or their changes of skin.
This, indeed, is a subject so replete with interest, and
which so fully displays the power, wisdom, and goodness
of the Creator, affording at the same time such large oc-
casion for nice investigation, that a pious and inquisitive
mind like yours cannot but be taken with it. In the
higher orders of animals, though the hairs of quadrupeds
and the feathers of birds are in many cases annually
renewed, the change, or scaling and increment of the
skin, is gradual and unperceptible ; no simultaneous re-

so as to destroy the included animal, but rather to facilitate its egress..
Those also of Coccinella Upunctata which I lately bred from the egg,
as soon as hatched began to devour the unhatched ones around them,
which they seemed to relish highly. I am mchned to believe how-
ever, that this unnatural procedure was to be attributed to the
cumstance of the female not having had it in her power to place her
eggs in the midst Aphides, their proper food.
N. Diet. d'Hist. Nat. xx, 359.

STATES OF INSECTS.

191

jection of it, in which it is stripped oft" by the animal it-
self like a worn shirt, being observable, till you descend in
the scale to the Serpent tribe which at certain periods
disengage themselves from their old integument, and start
forth with that new and deadly beauty so finely described
by the Mantuan bard : —

" So from his den, the writer slept away,
Shoots forth the burnished snake in open day ;
Who, fed with every poison of the plain,
Sheds his old spoils and shines in youth again :
Pi'oud of his golden scales rolls tow'ring on,
And dai'ts his forky tongue^, and glitters in the sun."

Pitt.

In these the new skin, I imagine, is formed under the
old from the rete mucosuni; but in insects, as I formerly
stated since the time of Swammerdam it has generally
been believed by entomologists, that the larva includes a
series of cases or envelopes, one within the other, con-
taining in the centre the germe of the future perfect insect,
whose development and final exclusion take place only
when these cases have been successively cast off". This
hypothesis, as was explamed toyou on a former occasion
has been controverted by a late writer, Dr. Herold ; who
affirms that the skins of caterpillars are also successively
produced out of the rete mucosum. I have however, I
hope, satisfied you that the old system is most consonant

* In the hxinian species, after certain fevers a simultaneous and
total moult, if the term may be so applied, takes place. I experi-
enced this myself in my boyhood ; when convalescent from Scarlatina,
the skin of my whole body, or nearly so, peeled off.

•> The translator, more ignorant of natural history than his author,
has turned the « Unguis micat ore trisulcis " of Virgil, into " darts his
forky sling."

" Vol. I. p. 70. i See above, p. 52—.

192 STATES OF INSECTS.

to nature and probability: but as we are now to enter
at large upon the Moults of insects, it will not be without
use if I add a few additional reasons which seem to me
still further to prove the correctness of Swammerdam's
system, as far as it relates to that subject. With regard
to the mere formation of the skin from the rete mucosim,
were this the whole question few would hesitate to adopt
the sentiments of M. Herold ; but when we come to con-
sider further— that the number of moults of individuals
of the same species is always the same, and that it varies
in different species, and takes place at certain periods,—
we begin to suspect that something more than the mere
formation of a new skin upon an old one being cast is to
be accounted for; and that the law which prescribes its
own definite number of skins to each species, must begin
to act in the primordial formation of the larva. Again,
the hairs observable in the higher animals do not take
their origin from the epidermis solely, but are planted
below it in the rete mm:osum, or deeper so that the
change of skin does not affect them ; but m the larvae of
insects they are a continuation of that integument, smce,
when the moult takes place, they always remain on the
rejected skin- this is the case, also, even with spines.
If you shave a caterpillar ready to change its skm, either
partially or generally, you will find that the part, m the
L skin that correspond with those that are denuded
are equally hairy with those that were not^; and if
you pav attention to the new-clad animal, you wUl find
farther; that the hairs never grow after a moult. From

Cuvier Ami, Co.p. u. 59G, N, Diet. d^Hist. NaL xxvi. 165.
bCuvici/Airf.624. cR,aum.i.l8...

STATES OF INSECTS.

193

hence it follows, that the //airs have their place and take
their whole m-owth between the new skin and the old
Whetlier the siiincs, simple or compound, lately described
to you, that arm some larvae are similarly circumstanced,
seems not as yet to have been ascertained ; but as the
spinous ones of certain Tenth-edines L. and Lepidoptera
at their last moult have no spines, the presumption is,
that, whether incased or not, they are mere appendages
of the skin on which they appear. A new set of hairs,
thei'efore, and probably of spines in spinous larvae, ac-
companying each skin, and these varying very much in ,
size, composition, &c. though a new membrane may be
admitted to be fonned from an action in the 7-ete inucosum
without a pre-existent germe of it, it seems not easy to
conceive how these hairs and spines can spring up and
grow there, each according to a certain law, without ex-
isting previously as a kind of corcidum orpunctim saliens;
and that the germes of the tubercles, in which the hairs
are so generally planted, according to a certain arrange-
ment and in a given number, should also pre-exist, seems
most consonant to reason. These and the several skins may
all co-exist in their primordial germes, and remain be-
yond the discovery of our highest powers of assisted vi-
sion, till a certain period when they may first enter the
range of the microscope-aided eye. It does not therefore
follow, because these jnimordia semina rei'wn are not
discoverable, that therefore they may not exist. Our
•acuities and organs are too limited and of too litde power
to enable us to see the essences of beine:.

Upon the supposition that the hypothesis of Swam-

^ iV. Did. (I'Hht. X,i/. vi. 2Q0.
VOL. in. o

194, STATES OF INSECTS.

merdam is the true one, we may imagine that the enve-
lope that lies within all the rest is that which covers the
insect in its pupa state. Above this are placed several
odiers, which successively become external integuments.
These changes or casting of the skin in larv^E, analogous,
as before observed, to that of serpents, are lamihar to
•every breeder of silk-worms, inwhich^r such changes
occur • the first at the end of about txmlve days from its
birth, and the three next each at the end of halfvh^i time
from the moulting which preceded it. With some ex-
ceptions % similar changes of the skin take place n. all
larvae, not however in the same number and at the same
periods. Most indeed undergo this operation only three
or four times; but there are some that moult oftener,
from five up to eight [Arctia viUica), nine [Callmorpha
Domimda), or even ten times ; for so often, M. Cuvier
informs us, the caterpillar of the tiger-moth iCaU^mo.'V^^
Caja) casts its exuvi.. It has been observed that the
caterpillars of the day-flying Lepidopera (f ^0
usually change only three times, while those of the mgh -
Zg ones (P/- L-) cl-Se>.-. The penods
that intervene between each change depend upon the
lencxth of the insect's existence in the larva state. In
tho^e which live only a few weeks or months, they are
from eight to twenty days; while in those that hve more
than a year, as the cockchafer, &c. they -e F^bab >
proportionably longer : though we know very httle with

^ Those Diptera whose metamorphosis is coarctate (Vol. I. p. 67),
bees the fe-le Cocci, &c. do not cast-their skin the larva state.
Reaum.iv.364 iV.!^. ^^iVJ.. X. 3^^^^^ ..

byces moult seven times.

STATES OF INSECTS.

195

regard to the moult of any insects besides tlie Lepido-
plera.

A day or two previously to each change of its skin,
the larva ceases eating altogether; it becomes languid
and feeble, its beautiful colours fade, and it seeks for a
retreat in which it can undergo this important and some-
times dangerous and even fatal operation in security.
Here, either fixing itself by its legs to the surface on
which it rests, or, as is the case with many caterpillars,
by its prolegs, to a slight web spun for this purpose, it
turns and twists its body in various directions, and alter-
nately swells and contracts its different segments. The
object of these motions and contortions seems to be, to
separate the exterior skin, now become dry and rigid,
from the new one just below it. After continuing these
operations for some hours, resting at intervals wdthout
motion, as if exhausted by their violence, the critical mo-
ment arrives : the skin splits in the back, in conse-
quence of the still more violent swelling of the second or
thif d segment : the opening thus made is speedily in-
creased by a succession of swellings and contractions of
the remaining segments : even the head itself often di-
vides into three triangular pieces, and the inclosed larva
by degrees withdraws itself wholly from its old skin.
All larvae, however, do not force their way through this
skin in precisely the same place. Thus, those of the haw-
thorn butterfly {Pieris Cratcegi), according to Bonnet %
make their way out by forcing ofl'what may be called their
skull, or the horny part of their head, without splitting the
skin, which remains entire; others have been observed
to make their way out at the side and the beUy. Reau.

' CEuvr. ii. 71.
O 2

196 STATES or INSECTS.

mur noticed the larva of Z^^na FilipeiMc^, previously
to its last moult, actually biting off and detaching several
portions of its old skin ; and before this, drops of a fluid
resembling water were seen to exude from it^

The skin when cast is often so entire, that it might be
mistaken for the larva itself; comprising not only the
covering of the main trunk with the hairs which clothed
it but of the very skull, eyes, antennas, palpi, jaws, and
legs- which, if examined from within, are now found to
be hollow, and to have incased, like so many sheaths,
similar parts in the new skin. That the feet of the newly-
coated larva were actually sheathed, as fingers in a glove,
in the same parts of the exuviae, maybe proved by a
very simple experiment: if a leg of one just ready to
cast its skin be cut off, the same limb will be found mu-
tilated when that change has ensued. The anal horns,
also, of the larv^ of the hawk-moth {Sphinx L.) and other
similar protuberances, are incased in each other in like
manner; but hairs are laid flat between the two skms,
and contribute considerably towards their more easy se-
paration. Thus, if you saved the skins cast by the larva
CalliMO^Tlia Caja, for instance, you would appear to
have ten different specimens of caterpillars, furnished
with every external necessary part, and differmg only m
size, and the colour perhaps of the hairs, and all repre-
sentina the same individual.

But further Ganges than this talce place. Swammer-
dai,t says, speaking of the moult of the grub ot 0,yctcs
„™n; a beetfe common in Holland, but not safs-
Zily Jscertained to inhabit Britain, " Not ung aU
nature's in my opinion a more wonderful s,ght than

•'. Rcaiun. 7i>.

STATES OF INSECTS.

197

chanse of skin in these and other the like worms. This
matter, therefore, deserves the greatest consideration,
and is worthy to be called a specimen of nature's mira-
cles ; for it is not the external skin only that these worms
cast, like serpents, but the throat and a part of the sto-
mach, and even the inward surface of the great gut,
change their skin at the same time. But this is not the
whole of these wonders ; for at the same time some hun-
dreds of pulmonary pipes within the body of the wonn
cast also each its delicate and tender skin. These sever-
ral skins are afterwards collected into eighteen thicker,
and, as it were, compounded ropes, nine on each side of
the body, which, when the skin is cast, slip gently and
by degrees from within the body through the eighteen
apertures or orifices of the pulmonary tubes before de-
scribed, having their tops or ends directed upwards
towards the head. Two other branches of the pulmo-
nary pipes that are smaller, and have no points of respi-
ration, cast a skin likewise." ..." If any one separates
the cast little ropes or congeries of the pulmonary pipes
with a fine needle, he will very distinctly see the branches
and ramifications of these several pipes, and also their
annular composition — Bonnet makes a similar obser-
vation with regard to catey-pillars ; but he appears to have
obsen-ed it more particularly, at least the change of the
intestines, previously to the metamorphosis of the insect,
when he says with the excrements it casts the inner skin
of the stomach and viscera ^. Both these great men ap-
pear to have recorded the result of their own actual ob-
servations with regard to the proceedings of two very dif-

Bibl. Kat. E. Trans A. 135. col. b. /.xxvu./, 6.

^ (Euvrcs,yin.Wi.

STATKS OF INSECTS.

ferent kinds of insects ; the one the grub of a beetle, and
the other the caterpillars of Lepidoptera. The account of
the former is given quite in detail, as that of a person who
is describing what he has actually seen : yet by a later and
very able physiologist, Dr. Herold, it is affirmed that the
inner skin of the intestinal canal is never cast, that canal
constantly retaining its two skins. He further affirms, that
they are only the large trunks of the Tracheae that cast
their skins, none being detached from their smaller rami-
fications \ When men so eminent for their anatomical
skill and nicety, and for their depth and acumen, dis-
agree, the question must be regarded as undecided till
further observations throw sufficient weight into one scale

or the other.

The larva which has undergone this painful process is
at first extremely weak: all its parts are soft and tender;
even the corneous ones, as the head and the legs, are then
scarcely more than membranous, and are all bathed with
a fluid, which, before the moult, intervenes between the
two skins, and facilitates their separation^: and it is
only afl:er some hmrs, or in some cases even daijs, du-
ring which it lies without motion, that this humidity eva-
porates, all its parts become consolidated, and it reco-
vers its strength sufficiently to betake itself to its wonted
food. Its colour, too, is usually at first much paler than
before, and its markings indistinct, until their tmts have

* EntwicMungsgeMte, &c. 34, 88. Swammerdam on the ccm-
T ihM" on the hinder part of the cast skm where it is

Ubi snpr. 136. col. a.
b N. Did. (CHvsf. Nat. vi. 200.

STATES OF INSFXTS.

199

been enlivened by exposure to the air, when they become
more fresh, vivid, and beautiful to appearance than ever.
When a few meals have invigorated its languid powers,
the renovated animal makes up for its long abstinence
by eating with double voracity.

A similar preparatory last, and succeeding state of
debility, accompany every change of the larva's skin.
Each time except the last, the old skin is succeeded by
a new one, with few exceptions, similar to the one ii lias
discarded. Previously to the final change, which discloses
the pupa, it quits the plant or tree on which it had lived,
and appears to be quite unsettled, wandering about and
crossing the paths and roads, as if in quest of some new
dwelling. It now abstains from food for a longer time
thaii before a common moult, empties itself copiously,
and as I have just said, if Swammerdam a:!d Bonnet are
to be depended upon, casts the skin that lines the sto-
mach and intestines, as well as that of the Tracheae.

I have observed above, that all larvas, with few excep-
tions, change their skins in the manner that I ha;ve de-
scribed. These exceptions are pi-incipally found in the
order Diptera^ of which those of the Linnean genera
Musca, (Estrus, and probably all that, like the maggot
of the common flesh-fly, have membranous contractile
heads, never change their skin at all, not even prepara-
tory to their becoming pupae. The skin of the pupa,
though often differing greatly in shape from that of the
larva, is the same which has covered this last from its
birth, only modified in figure by the internal changes that
have taken place, and to which its membranous texture
readily accommodates itself. The larvae of the Dipte-
rous genera Tipula^ Culex, and those which have corne-

200 STATES OF INSECTS.

ous heads, like other larvae change their skins several
times previously to becoming pupae \ The grubs, also,
of bees, wasps, ants? and probably many other H^/maio-
ptera, do not change their skin till they assume the pupa,
nor the larva of the female Coccus

If you feel disposed to investigate the reasons of that
law of the Creator which has ordained that the skms of
the higher animals shall be daily, and imperceptibly, and
as it were piece by piece renewed, while those of insects
are cast periodically and simultaneously,— the proximate
cause must be sought for in the nature of the two kmds
of skin, tha one being more pliable and admitting a
greater degree of tension than the other, and being so
constructed as to scale off more readily. If, ascendmg
higher, you wish to know why the skins of insects are so
differently circumstanced from our own, the most appa-
rent reason is, to accommodate the skin to the very rapid
growth of these animals, which a gradual and slower
change would have impeded too much, or the skm have
suffered constant dilapidation and injury ; therefore their
Beneficent Creator has furnished them with one which
will stretch to a certain point, and during a certain period,
and then yield to the efforts of the inclosed animal, and
be thrown aside as a garment that no longer fits the
wearer.

. And this leads me to a subject to which I am de-

a Reaum. iv. 604. ,t t- • '^a

Mbid 364. N.JDicLd'Hist.Nat.xx.36o. Hnhcr Fournm J 8.

M Hub^r does not say expressly that the grt,bs of ants >k..^i change
lir Sn ; but his account seems to in.ply that th^y change it oniv

previously to their metamorphosis.

STATES Ol' INSECTS.

201

sirous now to bespeak your attention, — the GroWh, I
mean, -and size of Insects in this state. As to size, larvae
differ as much as insects in their perfect state : these last,
however, never grow after their exclusion from the pupa,
while larvae increase in bulk in aproportion, and often with
a rapidity, almost without a parallel in the other tribes of
animals. Thus Lyonnet found, that the caterpillar of
the great goat-moth {Cossus ligniperda F.) after having
attained its full growth is at least 72,000 times heavier
than when it was first excluded from the egg*; and of
course had increased in size in the same proportion.
Connected with the size of larvas, is the mode in which
their accretion takes place. This, with respect to the
more solid parts, as the head, legs, &c., is not, as in other
animals, by gradual and imperceptible degrees, but sud-
denly and at stated intervals. Between the assumption
of a new skin and the deposition of an old one, no in-
crease of size takes place in these parts, while the rest of
the body grows and extends itself, till, becoming too big
for these solid parts, nature restores the equilibrium be-
tween them by a fresh moult in which the augmenta-
tion of bulk, especially in these parts, is so great, that we
can scarcely credit the possibility of its being cased in so
small an envelope. Malpighi declares, that the head of
a silk-worm that has recently cast its skin is four times
larger than before the change <=. It is very probable,
also, that when the outer skin becomes rigid, it confines
the body of the larva withhi a smaller compass than it
would expand to if miconfined, so that, when this com-
pression is removed, the soft and elastic new integu-

* Lyonnet 11. h jj-^^^ y^,^_ ogo.

De Bombi/cibus, 68.

252 STATES or IKSECIS.

ment imn.ediately swells out, and tbe a.iimal appears all
at once much larger than it was before the moult. In
tact, the proximate cause of the rupture and rejecfon of
the old skin is the expansion of the included body, «lnch
at length becomes so distended as t» split its envelope
aided, Indeed, as before described, by the corrtortmns of

the creature itself. r .1 •

The larvfB most notorious for the rapidity of their
crowth are those of Musca carnaria and otherflesh-fl.es:
feme of which Redi found to become from llO to more
than 200 times heavier in twenty-four hours ■ : an increase
of weight and si^e in so short a time truly prodigious,
but essential for the end of their creation-the rapid re-
moval of dead and putrescent animal matter. As tne
skins of these larvai are never changed, we may conclude,
if the cause of the change of skin in other larva: above
surmised be accurate, that their skins are more contrac-
tile and capable of a greater degree of tension than those
of larvae that are subject to moulting. And two pecuh-
arities observable in them confirm tlris ideal m the first
place, their head is not hard and corneous a. that of
L others, but capable of being shortened or lengthened ;
and in the next, their breathing-pores are not in the sides,
■ but at the extremities of the body, while in the ,nonlHng
larvre there are two in almost every segment, which must
form so many callous points that impede the stretching
of the skin to the utmost. The hairs, spines, and tuber-
cles, that are so often found on caterpillars, must also
form so many points of resistance that prevent that lull
IxtenL of 'the integument which it might otherwise
iidmit.

f Opuic. i. Ti.

STATES OF INSEC'J'S.

203

There is not always that proportion between the size
of larvas and of the insects that proceed from them that
might have been supposed, some small larvae often pror
ducing perfect insects larger than some of those proceed-
ing from such as are of greater size.

ix. As insects often live longest in the state we are
treating of, I shall say something next upon the age of
larvae, or the period intervening between their exclusion
from the egg and their becoming pupa?. This is exceed-
ingly various, but in every case nicely ada]3ted to their
several functions and modes of life. The grubs of the
flesh-fly have attained their full growth, and are ready to
become pupas, \\\ six or seven days ; the caterpillar of Ar-
gymiis Paphia, a butterfly, in fourteen days ; the larvae of
bees in tvacnty days ; while those of the great goat-moth
{Cossus Ugiiiperda) and of the cockchafer {Melolontha vul-
garis) Uve three years, or at least survive three winters, be-
fore the same ciiange. That of another lamellicorn beetle
{Oryctes nasico?-nis F.) is said to be extended to four or
J^ve ; that of the wire- worm {Elater segetum) to five.
That of the stag-beetle [Lucanus Cerms) is affirmed by
Rosel to be extended to six years ; but the most remark-
able instance of insect longevity is recorded by Mr. Mar-
sham in the Liimeayi Transactions ^ A specimen of Bur-
prestis splendida^ a beautiful beetle never before found in
this country', made its way out of a deal desk in an oflice
in London in the beginning of the year 1810, which had
been fixed there in the year 1788 or 1789; so that ac-
cording to every appearance it had existed in this desk

' Linn. Trans, x. 399.

204- STATES or INSECTS.

more than twenty years. Ample allowance being made
for its life as a pupa, we may conclude that it had existed
as a larva at least half the above period. The grubs of
the species of the genus C^nips L. attain their lull size
in a short time; but they afterwards remam five or six
months in the gall before they become pup^ \

With few exceptions it may be laid down, that those
larvae which live on dead animals, in fimgi, in dung, and
in similar substances, are of the shortest duration m this
state ; and that those which live under the earth, on the
roots of grass, &c. and in wood, the longest : the former
becoming pupae in a few days or weeks, the latter requir-
ing several months, or even years, to bring them to ma-
turity. The larv^ which live on the leaves of p ants
seem to attain a middle term between the one and the
other,-seldom shorter than a few weeks, and rarely
longer than seven or eight months. Aquatic larv^ ap-
pear to be subject to no general rule: some, as the larv^
of Gnats, becoming pup. in two or three
others, as those of the Ephemera, which are thus com^-
pensated for their short life as flies, in as many years .
Vhe cause of all these differences is obviously depend nt
on the nature of the food, and the purposes m the eco-
nomy of creation to which the larv. are destined.

X. The last part of the history of larvae relates to their
Preparations for assuming the pcpa state. ^ hen tliey
. 1.1 • f n e,Vo nffpr havim'- ceased to take
have acquired their full size, alter na\m^

the banks of rivers, perhaps they may be legauled as
economy of subterranean terrcdrtal larvs.

STATES OF INSECTS.

205

food, by a copious evacuation they empty the intestinal
canal, even rejecting- the membrane that lines it and the
stomach ^ ; their colours either change totally, or fade ;
and they make themselves ready for entering upon a
new stage of their existence. Some merely rest in a
state of inactivity in the midst of the substances in which
they feed, as if conscious of their inability to select any
safer abode. Of this description are most Coleopterous,
Hymenopterous, and Dipterous larvce, that feed under
ground, or in the interior of trees, fruits, and seeds.

But a still larger tribe, those which feed on leaves, ani-
mals, &c. act as if more sensible of the insecurity of this
to them important epoch. They are about to exchange
their state of vigour and activity for a long period of death-
like sleep. The vigilant caution which was wont to guard
them from the attack of their enemies will be hencefor-
ward of no avail. Destitute of all the means of active
defence, their only chance of safety during their often
protracted night of torpor must arise from the privacy of
their place of repose. About this, therefore, they exhibit
the greatest anxiety. Many, after wandering about as if

* A caterpillar nearly answering to the description of that of
Bomhyx cameUna, which I found upon the hazel, after a few days
produced sixteen grubs of some Ichneumon. At first these grubs were
green, but they became gradually paler ; and after a day or two be-
came pupas. But I mention this circumstance here for another rea-
son : upon examining them after this last occurrence, I observed that
they adhered to the lid of the box in which I kept the larva, arranged
somewhat circularly ; and at a little distance from the anus of each
was a pea-green mass, consisting of about eight oval granules, which
appeared like so many minute eggs. These were the excrement eva-
cuated by each grub previously to its becoming a pupa. The appear-
ance of this little group, with their verdant aiipenilage, formed a cu-
rious spectacle : they are still pupte, July 30,

206 , STATES OK INSECTS.

bewildered, retire to any small hole on the surface of the
earth, covering themselves with dead leaves, moss, or the
like, or to the chinks of trees, or niches in walls and other
buildings, or similar hiding-places. Many penetrate to
the depth of several inches under ground, and there form
an appropriate cavern by pushing away die surrounding
earth; to which they often give consistence by wetting it
with a viscid fluid poured from the mouth. The larvas
of other insects undertake long and arduous journeys in
search of appropriate places of shelter. Those of flesh-
flies, now satiated with the mass of putridity hi which
they have wallowed, leave it, and conceal themselves in
any adjoining heap of dust. The grubs of the gad-fly
{(Estrus) creep some of them out of the backs of cattle,
in tumours of which they have resided, and suffer them-
selves to fall to the earth ; while others, which have fed
in the stomach of horses, quit their hold, and by a still
more extraordinary and perilous route are carried dirough
the intestines the whole length of their numerous circum-
volutions, and are discharged at the anus. And without
enumerating other instances, various aquatic larvae, as
that of a common fly {Elophilus pendulm), &c. leave the
water, now no longer their proper element, and betake
themselves to the shore, there to undergo their metamor-
phosis.

Most of these, having reached their selected retreat,
require no other precaution; but another large tribe of
larvae have recourse to further manoeuvres for their de-
fence before they assume the pupa. Those of the aphi-
divorous flies {Syrphus F. &c.), of the various lady-birds
{Coccinellah.), and tortoise-beetles {Casstda L.), &c. hx
themselves bv the anus with a gummy substance to the

STATED OF isarxm.

ieave« or twigs under which lheypropf»>e to couc^aJ ilieiu-
Kelve« during their exisUaJcc in tiaat felate. fathers previ-
ousJy »u«[>eiid iiurms<;lv<;« by a siJkeii tlireax! fixed to tlie
tai),or;>a»Kingrouiultltel>ody; by which aJi>o, when become
j>upa?, tliey are afterwards }>eiident in a fsiinilar fK>«ition;
and lastly, a very great nurnlK;r of larvsa whoJJy incJo:->e
thern»>elve« in cases or coctXiUK, cf>mpx'>ed of silk and va-
rious other materials, by which during tlieir (state of re-
pow; they are proUxuA \)ot\i from their enemies and tlie
actioti of the atniosj;h(;re. As these tv/o iasfc-mentionetl
jirocesseij are extreniely curious and interesting, I shall
not fear tiring you by enUrring into some further detail
resj)ecting them : explaining/W/ the nKxle by whicli lar-
va; mxpt'7ul themselves, Ix/th lx;fbre and aft^r they are
bew)me pups*, by Kilkeii threads ; and next^ the various
cuKes or cocoont in which (Ahers inclose lliefAselves, and
their manner of oi)erating in tlie formation of them.

I. 'i'he larva; which suspend themselves and their pu-
pa*, with the exception of the triU; of AlucHa, a/)d some
Geometra; of the family of (}. pe7uLuUxria, jmiictaria^
are almost all butterflies \ So others follow this mode.
They may be divided into two great classes— those which
suspend themselves perpendicularly hy the tail, andtho)>e
which suspend thefuselves h(jrizontally by meaiiK of a

• Except some species of Polyomtnalm laix. {Tkecta, Ari^ynnisV.),
P. Arujolm, (:<mjib,n, &c., mul Hcjiperia IlulA, JieliJa: P., &c. Some
of the larva of the forrner become pupae within the staJk of some
plant, or partly wider the earth : those of tlie latter UbuaJly in a leaf
to which the abdomen is (kbtened by various threads, 'I'hese last
are the rouleiucx of the butterfly -tril>e, living, like some moths, in
leaves that tht^ have rolled up. .V. fJkf. d'Uist. Xat. xxiv. 499.

203 STATES or INSECTS.

threaJ !;irth«l lound their middle. In both cases it
should be observed, that die suspension of the pupa is
the object in view ; but as the process is the work of the
larva, this seems the proper place for explaming it. 1 o

begin with the> s« case.

You are aware that all kpidoptcrom larvaB have the
faculty of spinning silk threads from their mouths, and
it will readily occur to you that it is by means of these
tlrreads that they suspend themselves. But how How
is a caterpillar to hang itself by the tail to threads spun
from the mouth ? Even suppose this difficulty overcome,
others still greater remain. Suppose the caterpillar to
be suspended by its taU.-th-ui is but a prepa^-atory ope-
ration,-what is required is, that the pupa shall hang m
the same position : now when you take into consideration
drat it is incased witldn the skin of the larva, and without
feet or other external orgaus; that it has to extricate it-
self from this skin ; to hang itself in its place and to de-
tach the skin from the threads which hold it-th,s will
^ta no trifling task. Indeed at first view it seems
impossible. Country-fellows for a prize sometimes amuse
the assembled inhabitants of a village by runnmg races
* sals : take one of die most active and adroit o these
bind him hand .and foot, suspend huu by the bo torn of
his sack with his head downwards, to the branch of a
Ifty tree; make an opening in one side » *e sa*-
set him to extricate himself from it, to detach it lom
ts hold, and suspend himself by his feet m «s place.
Thou'h endowed with the suppleness of an Indian jug-
L, promised his sack full of gold for a reward, you
set him an absolute impossibility: yet this is what

STATES OF INSECTS.

209

our caterpillars, instructed by a beneficfent Creator, easily
perform. Their manoeuvres I shall now endeavour to
explain.

When the caterpillar has selected the under-side of
the leaf or other object to which it purposes suspending
itself, its first process is to spin upon it a little hillock of
silk consisting of numerous loosely interwoven threads ;
it then bends its body so as to insinuate the anal pair of
prolegs amongst these threads, in which, by a slight ex-
ertion, the little crochets which surround them ^ become
so strongly entangled as to support its weight with ease.
It now suifers the anterior part of the body to fall down,
and it hangs perpendicularly from its silken support with
its head downwards. In this position it remains often for
twenty-folu- hours, at intervals alternately contracting and
dilating itself At length the skin is seen to split on the
back near the head, and a portion of the pupa appears,
which by repeated swellings acts like a wedge, and ra-
pidly extends the slit towards the tail. By the continu-
ance of these alternate contractions and dilatations of the
conical pupa, the skin of the caterpillar is at last collected
in folds near the tail, lU^e a stocking which we roll upon
the ancle before withdrawing it from the foot. But now
comes the important operation. The pupa, being much
shorter than the catei-pillar, is as yet at some distance
from the silken hillock on which it is to be fastened; it
IS supported merely by the unsplit terminal portion of
the latter's skin. How shall it disengage itself from this
remnant of its case, and be suspended in the air while it
climbs up to take its place? Without arms or legs to

" Plate XXIII. Fig. 1. a.
VOL. III. p

210 STATES OF INSECTS.

support itself, the anxious spectator expects to see it fall
to the earth. His fears, however, are vain ; the supple
segments of the pupa's abdomen serve in the place of
arms. Between two of these, as with a pair of pincers, it
seizes on a portion of the skin; and bendmg its body once
more, entirely extricates its tail from it. It is now wholly
out of the skin, against one side of which it is supported,
but yet at some distance from the leaf. The next step it
must take is to climb up to the required height. For this
purpose it repeats the same ingenious manoeuvre, making
its cast-off skin serve as a sort of ladder, it successively
with different segments seizes a higher and a higher
portion, until in the end it reaches the summit, where
with its tail it feels for the silken threads that are to sup-
port it. But how can the tail be fastened to them? you
ask. This difficulty has been provided against by Crea-
,tive Wisdom. The tail of the pupa is furnished with nu-
merous little hooks pointing in different directions % as
.well adapted to the end in view as the crochets of the
larva's prolegs, and some of these hooks are sure to fast-
en themselves upon the silk the moment the tail is thrust
amongst it. Our pupa has now nearly completed its la-
bours ; it has withdrawn its tail fi-om the slough, climbed
up it, and suspended itself to the silken hillock— manoeu-
vres so delicate and perilous, that we cannot but admire
that an insect which executes them but once in its hfe,
should execute them so well: nor could it, as Reaumur
has well and piously observed, had it not been instructed
by a Great Master. One more exertion remains : it
seems to have as great an antipathy to its cast-off skin.

a Plate XXIII. Fig. 8. a.

STATES OF INSECTS.

211

as one of us should, when newly clothed after a long im-
prisonment, to the filthy prison garments we had put off.
It will not suffer this memento of its former state to re-
main near it, and is no sooner suspended in security than
it endeavours to make it fall. For this end — ^it seizes,
as it were with its tail, the threads to which the skin is
fastened, and then very rapidly whii'ls itself round, often
not fewer than twenty times. By this manoeuvre it ge-
nerally succeeds in breaking them, and the skin falls
down. Sometimes, however, the first attempt fails : in
that case, after a moment's rest, it makes a second, twirl-
ing itself in an opposite direction ; and this is rarely un-
successful. Yet now and then it is forced to repeat its
whirling, not less than four or five times : and Reaumur
has seen instances where the feet of the skin were so firmly
hooked, that after many fi-uitless efforts the pupa, as if
in despair, gave up the task and suffered it to remain *.
After these exertions, it hangs the remainder of its exist-
ence in this state until the buttei'fly is disclosed.

We are now to consider the second mode of suspen-
sion, in which larvae by means of a silken girth round
their middle, fix themselves horizontally under leaves, &c.
These follow the same process with that of those last der
scribed, in spinning a small hillock of silk to which they
fasten their hind legs ; and if the operation concerned the
larva state alone, this would be sufficient, as by means of
this support, and of their prolegs, they could easily re-
tain themselves in a horizontal position. But these lar-

* Bonnet is of opinion that tliis twirling process is not with any
view to get rid of the exuvise, but is caused only by the ii-ritation oc-
casioned by tlie spines of the skin of th'e caterpillar when they touch
that of the pupa. CEuv. ii. 109.

P 2

212 STATES OF INSECTS.

vse act as if they foresaw the assumption of a state in
which they will be deprived of legs. It is the suspension
of the forthcoming pupa that is the object in view ; and
though this can be hung by the tail in the same way with
those of the first class, yet it is plain that it cannot be re-
tained in a horizontal position, which for some unknown
reason is essential to it, without some support to its an-
terior extremity. It is necessary for the larva, therefore,
not only to fix its posterior legs amongst a collection of
silken fibres, but to spin a girth of the same material
round its body. This girth, though apparendy of a sin-
. gle thread, will be found on examination to be composed
of several, often as many as fifty or sixty; and is fastened
on each side of the body of the larva about the middle,
to the surface under which it is placed. Three different
modes of fixing these girths are adopted by the caterpil-
lars of different butterflies. Some, as those of the com-
mon cabbage-butterfly {Pieris Brassiccs), which have re-
markably pliable bodies, bend them almost double on
one side, then fix the thread and carry it over to the
other in the same position, repeating this operation as
often as is necessary. Others, as that of Lt/ca7ia Argus
and many more of the Papiliones Rurales and Urhico-
Icelu., which have a short and more rigid body, after
having bent the head on one side so as to fix one end of
the thread, bring themselves into a straight position, and,
by a manoeuvre not easily described, contrive to intro-
duce the head under the thread, which they then bend
themselves to fasten on the other side, pushing it to its
proper situation by the successive tension and contrac-
tion of their segments. But the most curious mode,
though mdeed that which seems most natural, is adopted

STATES OF INSECTS.

213

by the caterpillar of the beautiful swallow-tail butterfly
( Papilio Machaon) and others of the same family. This
first forms the loop which is to serve for its girth, and
then creeps under it. But the difficulty it has to surmount
is, to keep itself from being entangled in the fifty or sixty
fine distinct threads of which the girth is composed, and
to preserve them all extended so as to be able to intro-
duce its body beneath them. For this purpose it makes
use of the two first pair of its fore-legs, employing them
as a woman does her hands in winding a skein of cotton,
to collect and keep all the threads of its card unentangled
and properly stretched ; and it is often with great diffi-
culty, towards the end of the process, that it prevents
them fi*om slipping off. When a sufficient number of
threads is completed, the animal bends its head between
its legs, and insinuates it under the collected loop, which
by its annular contraction it easily pushes to the middle
of the body.

In about thirty hours after the larvae which girth them-
selves have finished their operations, the skin splits, and
the pupa disengages itself from it by those contractions
and dilatations of its segments which have been before
described, pushing the exuviae in folds to the tail, by dif-
ferent motions of which it generally succeeds in detach-
ing them. One would have thought there would be con-
siderable difficulty in slipping the skin past the girth ;
but this, according to Reaumur, seems to be easily ef-
fected

If you are desirous of witnessingforyourself the manoeu-
vres by which these curious modes of suspension are

* For the above account sec Reaum. i. Mevu x. xi.

214 STATES 01' INSECTS.

effected, you may be readily gratified. It is only neces-
sary to collect and feed until their metamorphosis the
black spinous caterpillars of the common peacock-but-
terfly {Vanessa lo), which in most places may be found
upon nettles, or those of the Pieris BrassiccE, which swarm
in cabbages or brocoli in every garden. The former will
exhibit to you a specimen of vertical, the latter of hori-
zontal suspension. It should be observed, however, tliat
to hit the precise moment when these processes are go-
ing on, it is necessary to feed a considerable number of
the larvae of each kind; some one of which, if you watch
them narrowly when they have attained their full growth,
you will scarcely fail to surprise in the act.

I must observe here, that although the vertical and
horizontal are the two principal positions in which cater-
pillars suspend themselves, yet that others are inclined at
various angles; and some are attached with less art, ap-
pearing only to be fastened by some part of their abdo-
men to the body upon which they are fixed \

2. The larvae whose procedures I am in the next place
to describe, are those which, previously to assuming the
pupa state, inclose themselves in cases or cocoons of diffe-
rent materials. For the sake of method, I shall divide
these into two great classes : First, those which form their
cocoons entirely or principally of silk; and secondly,
those which form them chiefly of other substances.

To begin with the>./. The larvae which mclose
themselves in silken cocoons are chiefly of the Lepido-
pterous tribes of Bmihycidce and NocinidcC; but a few

» N. Did. d'Hid. Nat. vi. 291—.

STATES OF INSECTS*

215

Geomctra [G. papilioniaria, ladearia, &c.); most of the
Hymeiioptera; some Coleoptera, as certain of the weevil
tribe {Hypera Arator, Bumicis Germ.), and those bril-
liant beetles frequenting aquatic plants constituting the
genus Donacia F.; the Neuropterous genera /fmeroSms
and Myrmeleon ; Mycetophila and a few others in the
Diptei-a ; and Piilex in the Aphanipta-a fabricate cover-
ings of the same material. In all, with the exception of
Myrmeleon and Hemerohius (and perhaps Hypei-a Runii-
cis, &c.?) which have their spinning apparatus at the
extremity of the abdomen, the silken thread employed in
forming these coverings proceeds from the middle part of
the under-lip, as before explained ; and is in fact com-
posed of two threads gummed together as they issue from
the two adjoining orifices of the spinner.

Of the larvae which inclose themselves in sillc, the most
familiarly known is the silk-worm : the cocoon of this
consists exteriorly of a thin, transparent, gauze-like coat-
ing, through the interstices of which can be seen an in-
ner, smaller, oval ball of a more close and compact tex-
ture. The whole is in fact composed of one single
thread, but arranged in two distinct modes. To form
the exterior envelope, which is merely the scaffolding by
means of which the inner and more solid covering is con-
structed, the caterpillar, after fixing upon a space between
two leaves or twigs or angles suitable for its purpose,
begins by glueing one end of its thread to one of the ad-
joinmg surfaces. This thread it next conducts to another
part and then fastens, repeating this process and inter-
lacing it in various directions, until it has surroimded it-
self with a slight and loosely spun netting. In the cen-
tre of this, when contracted into a space sufficiently small,

216

STATES OF INSECTS,

it lays the foundation of the inttrioi' cocoon. Fixing it-
self by its prolegs to some of the surrounding threads,
it bends its body, and by successive motions of its head
from side to side spins a layer of silk on the side oppo-
site to it : when this is of the requisite thickness, the larva
shifts its position, and repeats the same process in another
quarter, covering each layer in turn with a new one
until the ulterior cavity is reduced to the size desired.
Thus, the silken thread which forms this new cocoon is-
not, as might have been supposed, wound circularly as
we wind the thread of a ball of cotton; but backwards and
forwards in a series of zigzags, so as to compose a num-
ber of distinct layers. Malpighi could distinguish six of
these layers ^, and Reaumur suspects there is often a
greater number The former found the length of the
thread of silk composing them when v/ound offj without
including the exterior case, to be not less than 930 feef^;
but others have computed it at more than a thousand ^ :
consequently the threads of five cocoons united would be
a mile in length. Estunating by the weight, — the thread
of a pound of cocoons, each of which weighs about two
grains and a half, would extend more than 600 miles %
and such is its tenuity, that the threads of five or six co-
coons require to be joined to form one of the thickness
requisite in the silk manufacture. It is the continuous
thread of the inner cocoon which is most valuable ; the
outer loose coating from its irregularity cannot be

» De Bombyc. 54. i. 498.

^ De Bombyc. 43. " Did. d'Hist. Kat. s'l 294.

« Lesser. L. ii. 150, note 22. Boyle says an English lady found that
the silk of a single cocoon would extend 300 English leagues or 900
miles. But this must be a mistake.

STATES OF INSECTS.

217

wound off, and is known in commerce by the name of Jloss
silk.

Manoeuvres in their general principle similar to those
of the silk-worm are followed by most of those larvae
which inclose themselves in silken cocoons. Many spe-
cies, however, adopt variations in the mode of procedure
all of which it would be tedious to particularize, but some
of them are worth mentioning. The larva? of Tortrix
prasinana^ and other species of moths which form co-
coons resemblmg a reversed boat, arrange their threads
in layers, so as to construct two parallel walls gi-adually
inclining towards the top and ends, where they finally
force them to approacli each other by means of an appa-
ratus of silken cables ^. And the larva of Saturnia Pavo-
7iia, though it forms the base of its flask-shaped cocoon by
spinning like the silk-worm a number of intei*woven zig-
zags, places the threads which compose the interior fun-
nel-like opening of the apex nearly straight, parallel to
each other, and converging towards the same point in
the centre

These last, as well as almost all larvae, constantly re-
main in the inside of the cocoon during its construction.
But De Geer has given us the history of a minute cater-
pillar of a species of moth (Tinea L.) which feeds on the
under side of the leaves of the Rhamnus Frangula, or
Black Alder, that actually weaves half of its cocoon on the
outside. This cocoon, which is very small, is beautifully
fluted, consisting of several longitudinal cords, with the
intervals filled by fine net-work, and shaped like a re-
versed boat <=. The animal begins by laymg the founda-

" Reamn. i. 555—. ^ Plate XVII. Fig. 5, b.

' De Geer i. t. xxxii./. 3—6.

218

STATES OF INSECTS.

tions of one of the ends of her cocoon, she adds new
threads to this small beginning, and so proceeds. As
the work advances she retreats backwards, and her body
is situated nearly in the same line with the cocoon she
has begun, and quite out of it ; she only touches with her
head and legs its anterior margin. When half the co-
coon, or rather of its exterior layer, is finished, she sus-
pends her operations for some moments. She then for
the first time introduces her head into this demi-cocoon,
and turns herself in it by doubhng her supple body, and
passing one part over the other, so that at last she ma-
nages to bring her tail into the pointed end of the cocoon,
the head and the anterior half of her body remaining
without. Thus situated, she commences her operations
afresh. At a distance from the margin of the demi-co-
coon, equal to its length, she begins to spin the pointed
end of the other moiety, the length of her body serving
her as a measure that enables her to begin at tlie proper
distance from it. This new portion she spins in the same
manner as the other ; but as she is prevented by the demi-
cocoon in which the posterior part of her body is lodged
from retreatmg backwards, she contracts her body more,
which answers the same purpose. When the new work
is so advanced that she can no longer contract her body,
she bends the anterior part of it considerably, and re-
verses her head. When the distance between the mar-
gin of the two halves of the cocoon is very small, so as no
longer to admit the head between them, in order to unite
them she is obhged to have recourse to another manoeu-
vre. Withdrawing her head, she extends silken longitu-
dinal threads between the two margins, and thus unites
them. This part is more clumsy, and not so regular as

STATES OF INSECTS.

219

the rest of the cocoon, so that the pomt of union is always
discoverable. These caterpillars do not always divide
the cocoon into two equal portions, for often they will
finish three quarters of the cocoon before they enter it,
and begin at the other end ^.

The general rule is, — that each larva spins for itself a
separate cocoon ; but amongst those of Arctia chry&arhea
and others which live in society, two or three sometimes
begin their operations so close together that they are
under the necessity of forming one common cocoon, which
serves for a covering to the whole number. The same
thing happens to silk-worms, the double or treble cocoons
of which are called Dupions by the breeders. The larvae
of some Ichneumons, besides forming each its separate
cocoon, spin a joint cottony covering for the whole ^,
which is effected thus : — After they leave the caterpillar
they have devoured, they fix themselves side by side at a
little distance from it, and begin to spin each a cocoon ;
and in order to defend its end and side that is not covered
by others, they spin further an envelope of loose silk,
and thus this exterior covering is formed.

The size, figure, colour, substance, and textiu'e of
silken cocoons are extremely various. Their size indeed
is usually proportioned to that of the included larva or
pupa; yet it is by no means always so. Some large ca-
terpillars spin cocoons so small, that the observer can
hardly conceive how they can be contained in so narrow
a compass : Eriogaster Catax is a moth of this descrip-
tion And others smaller in size lodge themselves in

» De Geer i. 463—.

*> Reauni. ii. Mem. xi. Comp. De Geer ii. 163. Reaum. ii. 424.
B. Ca^oj.— Pupa arete follicuhita. Fab.

220

STATES OF INSECTS.

apartments apparently much more spacious than neces-
sary. The transparent hammock-Uke cocoons of Hejn-
alus Humuli and Arctia villica, two other moths, would
contain several of their pupas. I possess one in which
the pupa is suspended in the centre, that is ten times its
size, and not very short in dimensions of that of Attacus
Papliia^ a giant silk-moth. The largest cocoon I ever
read or heard of, is that thus described by Mr. Hobhouse
in his Travels: " Depending," says he, " from the boughs
of the pines, near the Attic mountain Parnes, and stretch-
ing across from tree to tree so as to obstruct our passage,
were the pods, thrice as big as a turkey's egg ! and the
thick webs of a chrysalis, whose moth must be far larger
than any of those in our country." If this statement
is correct, and I am not aware that there is any reason
for doubting it, the cocoon must be vastly larger than the
pupa, or the moth it produced would far exceed in size
any yet known. Perhaps, however, as this gentleman is
probably no entomologist, what he took for a cocoon
might be a nidus, in which many larvaj were associated,
■ of the nature of those formerly described ^

With regard to Jigure, the majority are like those of
the silk-worm, of a shape more or less oval or elliptic :
some, however, vary from this. That of Lasiocampa
Ruhi is oblong. 1 have one from New Holland some-
what resembling an acorn, fixed to the twigs of some tree
or shrub, of a very close silk, and covered by a circular
operculum, which the animal pushes off when it assumes
the imago; this is ovate or conico-ovate; others again are
globose"^; others are conical'', as that of Gastropacha

• Traveh in Greece, 285. " See above, Vol. I. p. 4/6— •

« Meriau Surinam, t. xv. ^ Reaum. ii. t. xxni./. o.

STATES OF INSECTS. 221

quercifolia ; others almost fusiform* [Odenesis potaioria).
Reaumur received one from Arabia which was nearly
cylindrical Those of T. prasinana before noticed, and
many other Tortrices, are shaped like a reversed boat ;
that of Saturnia Pavonia and others of the same tribe,
like a Florence flask with a wide and short neck. The
cocoon of Lygcena FilijJeJidula resembles a grain of bai-
ley. Another cocoon in my cabinet, of very slight net-
work, is shaped something like aai air-balloon. But the
most remarkable one for its form and characters, is one
that I received from the rich cabinet above quoted. This,
which is of an unusually close texture, is suspended by
a thread more than two inches long from the point of a
leaf; it then swells into a perfect cone, at the base about
four-fifths of an inch in diameter and half an inch in
length, and covered with scattered setiform appendages :
from the centre of the base projects a large hemispherical
protuberance, which terminates in a long stalk, much
thicker than the thi-ead that suspends the cocoon. There
is commonly no difference between the shape of cocoons
spun by larvae which are to give bii'th to different sexes of
the same species. The silk-worm cocoons, however,
which will produce male moths, have more silk at the
ends, and consequently are more round than those which
are to produce females : but the difference is not sti'ik-
ing.

The most usual colour of silken cocoons is white, yel-
low, or brown, or the intermediate shades. The whites
are very pure in the general envelope of some species

Ichneumonidce, and yellows often very brilliant. But

" Sepp. iv. t. viii./. 5. ^ Reaum. i. t. xliv./,2.

Plate XVII. Fig. 7.

222

STATES OF INSECTS.

besides these more general colours, some cocoons are
black ^, some few blue or green, and others red Some-
times the same cocoon is of two dilFerent colours. Those
^of certain parasites of the tribe of IcJmeumones minuti L.
the motions of one of which I noticed on a former occa-
sion are alternately banded with black or brown and
white, or have only a pale or white belt in the middle,
which gives them a singular appearance. In both cases
the difference in colour depends upon the different tints
with which the silky gum is imbued in the reservoirs :
the first portion of it is white, and with this the larva
first sketches the outline of its cocoon, and then thickens
the layers of silk considerably in those parts where the
white bands appear : when these are finished, its stock
of white silk is exhausted, and the remainder of the inte-
rior of the cocoon is composed of brown silk The cir-
cular operculum above mentioned as covering an acorn-
shaped cocoon, is paler than the latter, and also orna-
mented by a zone within the margin of deep brown.
The pale cocoon also of Attacus PapJiia is veined with
silk of a deep red.

I have very little to say on the substance of the silk of
cocoons. Though that of the silk- worm is composed of
such a slender thread, that of many others is still finer,
scarcely yielding in tenuity to the spider's web. On the
other hand, the silk of the cocoons of Saturnia Pavonia
and of several foreign species is as thick as a hair.

With regard to the texture of their cocoons — in some,
as in that of the silk-worm, the threads are so slightly

» I have a black one from Mr. Francillon's cabinet.
^ N. Diet. d'Hist. A^at. vi. 294.

= See above, Vol. II. p. 298—. " Rcaum. ii. 436.

STATES OF INSECTS.

223

glued to each other, as to separate with facility ; but in
that of the emperor-moth just mentioned they are inti-
mately connected by a gummy matter, fornished, as
Reaumur conjectures, from the anus ^, with which the
whole interior of the cocoon is often plastered. Some,
as that of the silk-worm, are composed of an exterior
loose envelope, and an inner compact ball ; others have
no exterior covering, the whole cocoon being of an uni-
form and thick texture. The larva of Cossus Uobinics
Peck, in spinnmg its cocoon, makes the end next the
opening to the air, by which the imago is to emerge, of a
slighter texture than the rest of it ^. The exterior case
is sometimes, as in Laria pudihunda., very closely woven,
so as to resemble a real cocoon ; its form is usually
adapted to that of the inner one; but in some which fix
them under flat surfaces {Laria fascelina, Callimorpha
Caja,) it resembles a hammock Cocoons of a close
texture have generally no orifice in any part ; but that of
Eriogaster lanestris is spun with openings, as if bored
fi-om without, the use of which, however, does not seem
to have been ascertained ^

Many silken cocoons are of so close a fabric, as, when
finished, entirely to conceal the included insect; but a
veiy considerable number are of a more open texture,
composed of a much smaller quantity of silk, and that
woven so loosely, that the larva or pupa may always be
discovered through it. Of this description are the co-
coons of Hypogymna dispar, Arctia Salicis, &c., which
consist only of a few slight meshes. Those of some oUiers

» Reaum. i. 503. •> Peck on Locust-tree Insects, GO.

Bonnet ii. 260. J Sepp. iv. t. ii./. 4.

« Brahm. Ins. Kal. 289.

224

STATES OF INSECTS.

resemble gauze or lace \ Of the first description is one
in my cabinet before alluded to, shaped somewhat like
an air-balloon; the meshes are large and perfectly square.
The pupa hangs m the centre, fixed by some few shght
threads which diverge from it to all parts of the cocoon —
so that it looks as if it was suspended in the air, lilce
Mahomet's coffin, without support. Of the second de-
scription is a black one with very fine and nearly circular
meshes : the threads that form these are thick, and seem
to be agglutinated. In our own country, the cocoons of
somebeetles, as QiHypera Arator^ Galeruca Ta7iaceti, ar)d
of some little Tinece, also resemble gauze. Many of the
larvse, however, which spin these cocoons, whose thin-
ness is probably attributable to the smallness of their
stock of silk, seem anxious for a more complete conceal-
ment; and therefore commonly either hide them between
leaves tied together, in some with a certain regularity,
in others without art^; or thicken their texture, and
render it opaque, by the addition of grains of earths
or of other materials with which their bodies sup-
ply them. These are principally of two kinds. The
larvee of Lasiocampa Neustria, Arctia Salicis, &c. after
spinning their cocoons, cast from their anus three or four
masses of a soft and paste-like matter, which they apply
with their head all round the inside of the cavity ; and
which, drying in a short time, becomes a powder that
effectually renders it opake. This is not, as might be
conjectured, an excrement, but a true secretion, evidently

• Plate XVII. Fig. 8.

b The thick cocoons of Attacus Paphia, Polyphemu.'!, &c. are also
thus fastened between leaves.
' Merian Europ. ii. /. ix.

STATES OF INSECTS.

225

intended for this very purpose : and, according to Reau-
mur, a similar powder, but white, derived from the vari-
cose intestines, is used by the caterpillars of GastropacTia
quercifolia^ &c. * The other material, which is still more
frequently employed, and which is occasionally mixed
with the former, is the /io?;- which everyone has observed
to cover so thickly the bodies of some caterpillars. This,
after spinning a sufficient envelope, they tear, or in some
instances cut off with their mandibles, and distribute all
round them, pushing it with their head amongst the in-
terstices of the silk, so as to make the whole of a regular
thick texture. After this process, which leaves the body
completely denuded, and often seems to give them great
pain, they conclude by spinnmg another tissue of slight
silk, in order to protect the forthcoming pupa from the
surrounding prickly points. It should be observed, how-
ever, that though many hairy larvae, as those of Noctua
Aceris, Arctia Caja, and others, employ their hairs m the
composition of their cocoons, the rule is not general,
several never making any such use of them. Nor do all
that do so employ them distnbute them in the same man-
ner as those above described, which rarely attempt to
arrange them in any regular position. Reaumm- has no-
ticed a small hairy caterpillar that feeds on lichens, which
is more methodical : this actually places its hairs upright,
side by side, as regularly as the pales in a palisade, in
an oval ring around its body, connecting them by a slight
tissue of silk, which forc-es them to bend into a sort of
roof at the top ; and under this curiously-formed cocoon
assumes its state of pupa \ Some larvse make so much

' Reaiim, ii, 284, b Ibid, i, 5.^4.

VOL. in, o

226 STATES OF INSECTS.

hair and so little silk enter into the composition of their
cocoons, that on the first inspection they would be pro-
,nounced wholly composed of it^* ; others, thickening the
interior of their cocoon with hair, line the whole with a
viscid matter like varnish ^.

The larvae of some saw-flies {Tenthredo L.) are re-
markable for inclosing themselves in a double cocoon, in
which the inner is not, as in the silk-worm &c., connected
with the outer, but perfectly distinct from it. Some spe-
cies, as T. Roses {Cryptus Jur.), which have but a small
stock of silk, compose the outer cocoon of thick silken
cords crossing at right angles, and forming an oval net;
which at the same time that it protects them effectually
from the ants, which are always ready to attack them, de-
mands much less silk than a covering of a closer texture.
But the tender nymph itself requires to be inclosed in a
case of a softer and more delicate substance ; and accord-
ingly the inner cocoon is composed of fine silk, woven
so closely that the threads are scarcely perceptible under
a microscope Reaumur mentions a hymenopterous
larva belonging to Latreille's Fossm-es {Sphex L.) which
thickened its cocoon with the legs, wings, and other rehcs
of the flies which it had devoured trophies— like the
drinkmg-cups of some savages, made of the skulls of their
enemies, or the skull -pyramid near Ispahan— of its
powers of devastation.

It is a general rule, that those larvas which spin co-
coons, never m ordinary circumstances become pup^
without having thus inclosed themselves. An exception,
however, is met with in the larva of a species of ant no-

a Bonnet ii. 397. ' Ibid. ix. 181.

cReaum.v.102. Mbid. iv. 269.

STATES OF INSECTS.

227

ticed by De Geer {Forynica fusca L.), some of the indi-
viduals of which inclose themselves in cocoons; while
others neglect this precaution, and undei'go their meta-
moiphosis uncovered Rose! also made nearly the
same observation on the larva of the flea

I must say something with regard to the situation,
often very remote from their place of feeding, in which
larvse fabricate their cocoons. A very considerable num-
ber, probably the majority, form them either partially
[Arctia lubricipeda) or wholly under ground; others
beneath dead leaves, moss, or in the chinks of the trees ;
others within the wood in substances on which they
have fed ; the larva of Cossus leaves in these a communi-
cation with the open air by which the imago emerges ;
and a large number attach them to the leaves and
branches of trees and plants; the cocoon of Donacia fas-
ciataQ) is fastened by one side to the roots or surculi of
Typha latifolia. There is usually nothing very remark-
able in the mode of fixing them, the exterior threads
being merely gummed irregularly to different portions of
the objects which support them. But some effect this with
greater art. I have one fi-om New Holland, very long,
which is suspended fi*om a twig by a long riband, as it
were, which entirely girths the twig. The larva of the
magnificent silk-moth, Attaciis Pajjhia, actually forms a
solid silken stalk to its cocoon, an inch and half in length

» De Geer ii. 1084. Comp. Ray Hist. Ins. Prgef. xi. It is the opi-
nion of M. P. Huber, that in this case the nahcd pupae are deprived
of their cocoons by the neuters : he states, indeed, that he has often
seen them pulled off' by them, and also by those of i^'. cunicularia ;
and he seems to think that these larvae are never developed. Mcetirs
des Fourmis, 84. note 1 .
II, viii. 16.

228 STATES OF INSECTS.

and a line in diameter, fastened by the other extremity
to a twig, which it closely sm-rounds as if with a ring,
at first sight resembling a fruit of a very singular ap-
pearance =*. I have specimens of this cocoon with both
stalk and ring. A bell-shaped cocoon fastened by a foot-
stalk, but of softer consistence, to a blade of grass, found
by Mr. Sheppard, I can also show you ; and my friend
Mr. Wilkin had a similar one out of the late Mr. Hud-
son's collection. Most larvae spin their cocoons in soU-
tude: some of those, however, which live in society do it
close together under their common tent.

There are other cocoons that should be noticed here,
such as those formed by the larva of Zygana Filipendulce,
and some Bomhyces, saw-flies {Tenthredo L.), and bee-
tles {Curculio, Donacia R), &c. These are formed of
a substance which seems more analogous to gum than
silk, yet furnished from the silk reservoirs, and usually
present the appearance externally of parchment or mem-
brane. That of the insect first mentioned is coated,
however, with a slight interior silken lining; as indeed
are ahi^ost all cocoons, of whatever substance.

The second class, into whieh I have divided larvae that
inclose themselves in cocoons, includes those which form
their coverings not solely or principally of silk, but in
which other materials are mixed more or less. The co-
coons of some of these larvae are merely composed of a
few leaves slightly tied together, either irregularly, or ar-
ranged, particularly when they ai e of a linear figure, with
considerable symmetry. The grubs of many beetles, as of

« Linn. Trans, vii. f. n.f. 5, 6.

STATES OF INSECTS.

229'

the rose-beetle, Cetonia aurata, &c., prepare themselves a
cocoon, composed of earth, pieces of rotten wood, and any
substances within tlieir reach; which they fasten together
with a glutinous secretion. The same material is employed
by others in forming a cocoon wholly of earth; which
is sometimes, as that of the stag-beetle, Lucanm Cer-
vus, exceedingly hard ; at others, as that of some moths,
Noctua ambigua, &c., so slight as to fall to pieces as soon
as touched ^. Other cocoons are formed of grains of
earth. Reaumur has given a very interesting account of
the procedures of a larva in repairing one of these co-
coons, from which he had broken off the top when just
completed. Without quittmg the interior of the M'alls
that remained, it put out its head from the breach, and
for more than an hotir employed itself in selecting one
by one grains of earth, which it conveyed with its mandi-
bles and deposited within its case : it next spun all round
the opening threads of silk, to which it attached grains
of earth taken from the previously-stored heap, uniting
diem compactly by means of other silken threads. After
employing three hours in this laborious process, the in-
dustrious little mason had reduced the diameter of the
breach to a few lines. Reaumur was very curious to
know how it would fill up this orifice, which would no
longer admit the protrusion of its head outside the walls,
as in its previous operations. He concluded, that while
the rest of the cocoon was exteriorly formed of earth,
this opening would be merely closed with silk. He was
mistaken, however: the artist knew how to vary its

» Wien. Verz. I possess a cocoon of this kind from New Hol-
land, even now quite solid, and retaining its form. No silk appears
to have been used in its composition.

230

STATES OF INSECTS.

niuuoeuvres, and make its vault of one unil'orni texture.
It spun across the opening a little net of silk, between the
meshes of which it thrust grains of earth so dexterously
that they projected as far as the outer surface, retained
there probably by silken lines previously attached and
fastened within. It then finished its habitation by forti-
fying the inside of the orifice with another layer of earth
The ant-lion [Myrmeleon) spins a globular cocoon with
its anus, which it covers with grains of sand^. One that I
took in the forest of Fontauiebleau, in the quarry that pro-
duces the crystallized sandstone called the Fontainehleau
fossil, was covered with large and shining grains. Instead
of the grains of earth or sand employed by these larvae,
those of another tribe substitute grains of stone detached
from the softer walls, upon whose lichens they previously
feed, which they unite into solid oval cocoons Those
of a fourth form their cocoons of patches of short moss
arranged with the roots downwards, and forming a vault,
as it were, of verdant turf, admirably adapted for con-
cealment The larvae of some moths form their cocoons
of irregular pieces of bark tied together with silk, and
resembling when completed a knotty protuberance of the
twig on which they are fixed. That of Pyralis tubercu-
lana constructs a pannier-shaped one of the parenchyma
of the leaves of plants ^.

All these cocoons, however, must yield in point of
singularity of construction, materials, and ingenuity, to
one formed by a small caterpillar, described by the illus-
trious naturalist lately quoted, which feeds upon the oak.
This cocoon is wholly composed of small rectangular

» Reaum. i. .579. " Ibid. vi. 368. ' Ibid. i. 542.

^ Ibid. 543. ' Linn. Trans. \. 1!)6.

STATES OF INSECTS.

221

Strap-shaped pieces of the fine upper skin, or epidermis
of the twig upon which it rests, regularly fastened to each
other in a longitudinal direction with very slender silken
cords. But the mode of its construction is even more
remarkable than the substance of which it is fabricated.
The caterpillar's first process is to form its slips of bark
into two flat triangular wing-hke pieces, projecting oppo-
site to each other from each side of the twig, somewhat
like the feathers of an arrow. It does not, perhaps, re-
quire any great degree of intelligence in a larva to give
its cocoon the usual oval form, when it begins to arrange
its materials in that shape fi'om the very first, and round
so good a mould as its own bent body; but we surely must
admit that it is a task to which no stupid artist would be
competent, to form first a multitude of strap-shaped la-
minse into two triangular plates, and then to bend these
plates into a case resembhng the longituduial section of a
cone, with an elliptical and protuberant base, — the figure
which the cocoon of this uisect assumes. All the nimu-
tise of the manoeuvres which it employs in this nice ope-
ration could not be comprehended without a more cUffuse
explanation than I have here room to give : suffice it to
say, that the caterpillar fastens silken lines to each exterior
opposite and longer side of the lamina!, and by applying
all the weight of its body forces them to bend and ap-
proach each other, in wliich position it secures them by
other shorter lines. It next repeats the same process
with the upper and shorter sides of the plates ; which
when joined form the base of the cocoon. Both these
tasks are accomplished in less than an hour, and the seams
are so nicely joined as to be imperceptible. A fine inner
tapestry of silk, covering all the asperities of the exterior

232

STATES OF INSECTS.

Avails, concludes its labours It is to be lamented that
Reaumur was unacquainted with the moth that proceeds
from the pupae inclosed in these ingenious cocoons ;
which being small, and precisely of the same colour as
the bark of the twig that supports them, are not to be
discovered but by a very narrow inspection. It would
seem, however, to be Noctua Strigula of Berkhausen,
Pyralis strigulalis of Hubner The larva, he informs
us, is found in May : its body is flatter than common, of
a yellowish flesh-colour, clothed with tufts of red hair on
each segment, and furnished with fourteen feet. Should
this description enable you to detect it upon your oaks,
a view of its ingenious procedures would amply repay
you for the trouble of seeking for it. The larvae of Ce-
rura vinula, Staurojms Fagi, and several other moths,
form their cocoons of grains of wood gnawed from the
trees on which they feed. These grains they masticate,
mixed with a glutinous fluid secreted from the mouth,
into a paste, which forms a covering of an uniform smooth
texture, and so hard as not readily to yield to a knife.
Of a substance apparently nearly similar is composed
the cocoon of a weevil related to Lipariis Pini ; which
with its inhabitant was given me by the ingenious Mr.
Bullock. A little moth, whose ravages have been before
noticed '^j lines the interior of the grain of barley, of
which it has devoured the contents, with silk ; divides it
into two apartments, into one of which it pushes the ex-
crement ithad voided, and in the other assumes thepupa''.
These, and the other larvae mentioned above, com-

" Reaum. i. 545—. ^ PyraL 8.3. t. iii./. 16.

<= See above, Vor. I. p. 1/2—.
Jleaum. ii. 491.

STATES OF INSECTS.

253

monly form their cocoons of the substances I have indi-
cated ; but when by any cause they are prevented fi-om
access to them, they often substitute such other materials
as are at hand. Reaumur fed a larva that formed its
cocoon of minute fragments of paper, vk^hich with its
mandibles it had cut from the piece that covered the glass
vessel that contained it * : and the same circumstance
happened to Bonnet.

Upon a former occasion I described to you the cases
of various kinds formed and inhabited by the insects of
the Trichoptera Order {Phryganea L.) commonly called
case-worms As these serve for the pupa as well as
the larva, they may be regarded as a kind of cocoon. I
shall not repeat here what I then said ; but having pur-
chased from the collection of the late Mr. Francillon
some that seem to belong to this or some cognate tribe,
that are of a curious construction, I shall give j'ou some
account of two or three of them in this place. The first
is not quite three inches long, of a sublanceolate shape,
but rather widest towards one end. It consists of an in-
ternal tough and thick bag or cocoon, of a silk resem-
bling fine wool of a dirty white colour, which is closely
covered transversely by pieces of the stalk of a plant,
about three-fourths of an inch in length, and crossing
each other at an obtuse angle. The next is thicker and
shorter: the internal bag is just covered with small frag-
ments of wood Hke sawdust ; over these are fastened ir-
regularly, short stout pieces of a pithy stick or stalk, and
the whole is clothed with a very close-woven ash-co-
loured web. It seems difficult to conceive how the in-
closed animal could contrive to cover her habitation with
' Rcaum. i. 540. »> See above, Vol. F. 46/—. II. 264.

234-

STATES or INSECTS.

this web without going wholly out of it. The third is
the most curious and remarkable of all. It is nearly six
inches long, and about four-fifths of an inch in diameter.
It consists of a bag of thick cinereous silk web, to which
are fastened, in a sextuple series, pieces of stick about an
inch long, the end of one mostly resting upon the base of
another: between each series a space of about three-tenths
of an inch intervenes, but at the apex they all converge.
This probably imitates the branch or stem of some tree
or plant, in which the leaves are linear, and diverge but
little from the stem. A label upon it states its country to
be New Holland. I suspect the inhabitants of the two
last cocoons to be terrestrial animals : the first is proba-
bly a true aquatic case-worm.

The same purpose for which the cocoons above de-
scribed serve, is answered in the case of numerous Di-
yterous insects, by a humble and less artificial contriv-
ance— the skin, namely, of the larva ; which, as was be-
fore observed ^, is never cast, but, when the insect is about
to enter into the pupa state, assumes a different form and
colour ; becomes of a thicker and more rigid texture ;
and defends the included pupa, which is separate from it,
till its exclusion. In this case the mouth of the larva is
constantly different from that of the perfect insect, or at
least has not with it those relations as to number and
kind of organs, which have been observed in the mouth
of other larvae compared with the insects that they pro-
duce. The animal, immediately after it is clothed with
this skui, if it is opened, exhibits only a soft gelatinous

» See above. Vol. I. p. 67.

STATES OF JNSECTS.

235

pulp, in the surface of which the exterior organs of the
adult insect cannot yet be detected. Nature requires
more time for their elaboration, or at least for the ap-
pearance of their outline, and to consolidate them. This
pulp first takes an oblong form {Boule allongee Reaum.),
and afterwards that of the insect it is destined to give
birth to ^ The skin of the larva also serves for a cocoon
to the pupae of male Cocci ^. The grub of the genus An-
threnus, so destructive to our cabinets of natural objects *=,
when it assumes the pupa does not quit its skin, but only
splits it open longitudinally on the back, and when it
becomes an imago makes its exit through the orifice ^.
Some Lepidopterous larvae even (Alucita pentadactylct,
Callimorpha rosea, &c.) assume the pupa state within
their last skin ^.

When a larva has finished its cocoon, — which with

» N. Diet. d'Hist. Xat. xvi. 269—. xxii. 76.

•> Reaum. iv. S2. The author here quoted asserts that the grub of
Ichneumon Lurvarum L. retains its skin, which, he says, is so trans-
parent that the form of the nymph can be seen through it. Ibid. ii.
447. De Geer, however, found that this really did cast its skin,
which is so transparent as to be scarcely visible, by pushing it gradu-
ally towards the anus, where it soon dries up and cannot then be dis-
covered. De Geer ii. 893 — . According toRosel the same cuxum-
stance attends the transformation of Coccinella renipmtulata Illig.
(C. Cacti Ent. Brit.), which at first perplexed liim not a little. It is
probable that in this case the retention of the skin was accidental ;
for some of the grubs of a MycetophUa, the transformation of which
I observed, became pupae within their last skin, while others wholly
disengaged themselves from it. The cause of this variation, I con-
jectured, arose from the former being too weak to extricate them-
selves from the skin.

See above. Vol. I. p. 238. Byrrhus Musasorum belongs to this
genus.

N. Diet: d'Hist. Nat. ii. 161. Pczold. 102.

236

STATES OF INSECTS.

some species, that proceed so earnestly as though they
had not a moment to lose, is the work of a few hours, of
others about two or three days, — after a certain interval
it casts its last skin, which is usually suffered to remain
in the cocoon (but which one moth, Geometra lacei'linaria,
ejects through an opening purposely left in its bottom),
and the pupa makes its appearance This interval is
exceedingly various. Most larvae assume the pupa state
within a few days after they have formed their cocoons ;
but some not for several weeks, or even months. The
caterpillar oiBomhyx cceruleocephala, according to Rosel,
lies three weeks in the cocoon before this change is ef-
fected ; those of many Piqnvora and Diploleparia Latr.,
according to Reaumur, six months ^ ; that of Phalana
tirticata nine months'^; and that of Cimbex lutea, accord-
ing to De Geer, sometimes eighteen months Brahm
observes, that such larvae of the double-brooded moth,
Hepialus Testudo, as form their cocoons in autumn, do
not become pupae until the following spring; while those
which form them in summer undergo this change in a
few day3^ From this fact it might be conjectured, that
the degree of heat prevailing at the time the insect in-
closes itself detei-mines the period of the pupa's appear-
ance ; but this supposition seems contradicted by what
Reaumur observed of a brood of the larv^ of Phalaria
urticata^ just mentioned, which, though they formed
themselves cocoons in September, did not become pupas
till the June following ^ I am unable, therefore, to as-
sign any plausible cause for these extraordinary varia-

* De Geer i. 339 — . Reaum. ii. 423, and iii. 497.
« Ibid. i. 605, '' De Geer ii. 941.

• Brahm Insek. 73. ' Reaiuii. ubi supra.

STATES OF INSECTS.

237

tions. The difficulty of comprehending how animals be-
fore so voracious can live so long without food may be
partly surmounted, by adverting to the circumstance of
its having attained its full growth, and laid up a store of
nutriment for the development of the perfect insect. It
is consequently no more wonderfid that it should not
have need of any further supply without casting off its
upper integument, than that it should not eat after hav-
ing done so and become a pupa.

LETTER XXXI.

STATES OF INSECTS.

PUPA STATE,

We have now traced our little animals through their
egg and larva states, and have arrived at the third stage
of their existence, the Pupa State. This, to include all,
can only be defined,— that state intervening between the
larva and imago, in which the parts and organs of the
perfect insect, particularly those of sex, though in few
cases fully developed, are prepared and fitted for their
final and complete development in the last-mentioned
state ; and in which the majority of these animals are
incapable of locomotion, or of taking food.

Pupae, like larvae, may be separated into two great di-
visions : —

I. Those which, in general form, more or less resem-
ble the larvae from which they have proceeded.

11. Those which are wholly unlike the larvje from
which they have proceeded.

I, To the first division belong, with some exceptions %

» In the Hcmiptcra the male Cocci (Reaum. iv. 32.) and Aleyrodes
(Ibid. ii. 311.) belong to the second division.

STATES OF INSECTS.

2S9

the Dermaptera, Orthoptera, Hemiptera, and most Apteray
with the neuropterous tribes of Libellulina, Ephemerina^
and the genus Termes, in the class Insecta; and the majo-
rity of the Arachnida. This, Uke the first division of
larvae, may be subdivided into two corresponding smaller
sections ; the first including those pupae which resemble
the larvae, except in the relative proportion and number
of some of their parts ; and the second those that resem-
ble them, except ui having the rudiments of wings, or of
wings and elytra.

i. The first subdivision will include the pupae, if they
may be so called ^, of insects of the Aptei^a order, and of
the class Arachnida : as, lice, PodurcE, Lepismida, centi-
pedes, millipedes, mites, harvest-men, spiders, scorpions,
&c. These mostly differ from their larvae only in that
the relative length or number of their legs, the number of
the segments of the body in some, or the development of
their palpi, more nearly approach the characters of the
perfect insect ; and in that while in their larva state they
have two or more skins to cast, previously to their assump-
tion of the imago, in their pupa state they have but one.
In fact, this last circumstance is the only one which,
strictly speaking, characterizes the pupas of this subdi\d-
sion ; as the changes which take place in the number and
proportion of the organs are partly produced with each
change of the larva's skin. And hence, as it is not easy
to ascertain what number of skins a spider, for example,
has yet to cast, and as both the larva and pupa dilFer so
little from the perfect insect, it is very difficult to deter-
mine in what state insects of this division are. From

* The terms larva and pupa, applied to the insects of this subdivi-
sion, are perhaps not strictly proper.

24-0

STATES OF INSECTS.

this difficulty has probably arisen the too great multipli-
cation of species in some of these tribes, particularly the
Arachnida^ the larva and pupa having been mistaken for
perfect insects. The pupae of this subdivision were
named by Linne complete, from the near resemblance
which they bear to the imago.

ii. The second subdivision will include the pupae of
the Dermaptera, Orthoptera and Hemiptera orders, with
few exceptions ; as likewise the Libellulina, Ephemerina,
and Tei-mitina ? amongst the Ne^iroptei'a : including the
well-known tribes of earwigs, cockroaches, crickets,
grasshoppers, locusts, Ian thorn-flies, froghoppers (Ci-
cada L.), bugs, plant-lice, dragon-flies, day-flies, white
ants, &c. Of these, as in the former subdivision, the
pupae are equally capable of eating and moving with the
larvae, which they resemble, except in having the rudi-
ments of wings, or of wings and elytra. The pupae of
the three orders first enumerated differ from those of the
Neuroptera in resembling the perfect insect in most in-
stances, both as to shape and the organs for taking their
food ; and in all other respects, except in not having their
wings and elytra fully developed ». The resemblance of
the pupae of the Libellulina and Ephemerina to the per-
fect insects is more distant, and the above organs in the
two states are very dissimilar ; for the pupae of the former
are furnished with a prehensory mask similar to that of
the larvae before described ^ which the perfect insect has

^ The larvse and pupae of many of the homopterous section of Hemi-
ptera differ often from the imago, not only in their fore-legs (Plate
XVf Fig. 4.), but also in other respects. I have the larva of a Ce7,-
trotus from Canada, given me by Dr. Bigsby, which has a long anal
process or tail. " Sec above, p. 125-.

STATES OF INSECTS.

241

not ; and those of the latter with the usual oral organs of
masticating insects, of which the imago has scai"cely the
rudiments.

I have applied the term rudime7its to the wings and
elytra in this state, not in a strict sense, but merely to
denote their appearance ; for m fact the wings, &c. are
complete, but only folded up longitudinally and trans-
versely, and inclosed in membranous cases, which when
the last change takes place remain attached to the pupa-
rium or pupa-case. The tegmina or hemelytra in this
state usually cover the wings, and the upper wings the
under ; but in the Libellulina both are usually visible.
Though commonly very small compared with the instru-
ments of flight in the perfect insect, some of these rudi-
ments, contrasted with the majorit}', are of considerable
magnitude. This is the case with those of some species
of Chermes., as we learn from De Geer ^.

II. The second grand division comprises by far the
largest number of pupae : those of all coleopterous, strepsi-
pterous, lepidopterous, hymenopterous, dipterous, and
aphanipterous, and by far the majority of neuropterous in-
sects, as well as the hemipterous genus Aleyrodes, and one
sex of Coccus of the same order. These pupae, however,
though agreeing in the circumstance of being unlike the
larvae fi'om which they proceed, differ from each other in
several respects, and require to be divided into three
great sections, as under: —

i. Those pupae in which the parts of the future insect,
being folded up under a membranous skin closely apply-
ing to each, are distinctly visible. To this head belong

VOL. III.

» iii. 135.

STATES OF INSECTS.

aenerally, the pupae of coleopterous- and hymenopterous
Lsects ; those of the neuropterous genera Myrmelcon and
Hm^oim, &c. ; the Trichopte^^a; amongst the Dipt era,
Culex, Tipula L., Tahanns, Bomhylius, &c. ; and that of the
flea {Pulex). These were the incomplete pupjB of Linn6.

ii. Those pupae in which the parts of the future insect,
being folded up under a harder skin, are less distinctly
discoverable. To this subdivision belong the pupae of all
Lepidoptera, and of them alone. These are what Linne
termed ohtected pupae.

iii Those pupae which are inclosed in the thick and
opaque skin of the larva, through which no trace of the
perfect insect can be discovered. These, which Lmne
termed coarctate pup*, include a large proportion of the
dipterous genere^i as (EstrusU Musca U Empts U
Conops L., &c. &c.

a The pup^ of Cassida, Imatidium, &c. seem to vary somewhat from
this tyje. the npper part being neither membranous nor exh^bmng
distinctly the foi-m of the inclosed imago.

^ m following arrangement of pup. is perhaps - ^P^^
better than that above given. But it is scarcely possible to propose
one free from objections.

t^l"^cept in proportion and number

. ^''Sxcept in proportion {Lice, Podur., Mites, Spiders,

2. EZplTj'opttion and immher (Centipedes, MiUe-
pedes).

ii With rudiments of the organs of flight. r , •

1. With oral organs resembling those of the perfect m-

sect (Hemiptera). „

2. With oral organs differing from those of the perfect

insect {Libelhda L., Ephemera L.).
II. Incapable of eating and walking.

i. Incomplete pupsE.

ii. Obtected.

iii. Coarctate.

STATES or INSECTS.

243

I shall next advert, chiefly to the pupae of the grand
division last described, under the distinct heads of sub-
stance, ^figure, and parts colour, age, sex, motions, and
extrication of the perfect insect.

i. As to their substance — at first interiorly all pupjE
consist of a milky fluid, in which the unformed members
of the future perfect insect may be said to float, and in

Lamarck divides the pupae of insects that undergo a metamorphosis
into tliree kinds, wliicli he names — Chiysalis, Mumia, and Nympha.

i. Chrysalis. Under this denomination he includes all inactive
pupae inclosed in an opaque puparium which entirely conceals them.
These he further subdivides into two kinds.

1. Chrysalis signata. This term is synonymous with the Pupa
obtecta of Linne, or the Chrysalis of Lepidojitera and some Diptcra.

2. Chrysalis dolioloides. Equivalent to the Pupa coarctata Linn,
peculiar to those Diptera that assume this state in the skin of the
larva.

ii. Mumia. All inactive pupae which are covered by a transparent
skin, through which all the parts of the inclosed imago may be seen,
subdivided also into two.

1. Mumia coarctata. Corresponding with the Pupa incompleta
Linn., which includes the Coleoptera and most of the Hymenoptera.

2. Mumia pscudonympha, confined to the Pupa of Phrygnnea and
some others. This might be named Pupa subincompleta.

iii. Nympha. Under this denomination are included all insects
that undergo only a partial metamorphosis, and are active in their
pupa state, corresponding with the Ptipa semicompletalAm. and also
subsemicompleta MacLeay. See Anim. sans Vertebr. iii. 285—.

M. Latreille has started an ingenious idea on this subject with re-
gard to these kinds of metamorphosis, which comprehends both larva
and pupa under a distinct denomination : as thus—

1. Demilnrve and DeminymjA synonymous with the Semicovtplete
Metamorj)hosvt.

2. Lnrve and Nymph, answering to Incomplete Metamorphosis.

3. CaterpUlar and Chrysalis, answering to Obtected Metamorphosis.

4. Vermilarve and Pupa, answering to Coarctate Metamorphosis.
N. Did. d'Hisf. Nat xvi. 272.

R 2

244- STATES OF INSECTS.

which they may be discerned, and separated with the
point of a pin \ In proportion as these acquire consistr
ency, and are more and more developed by the absorp-
tion of the surrounding fluid, they occupy its place, and
fill up the cavity of the puparium. The rest of this fluid
passes off by transpiration ^. Reaumur is of opinion that
it is from the epiploon, or corps graisseux, that this matter
is prepared, which he regards as analogous to the white
of an egg <=. In coarctate pupae the included animal, or
the pulp^that contams its germes (in which the limbs and
body at first are not discernible), fills at this period the
whole skin-cocoon; but in proportion as the above eva-
poration takes place, and the consolidation of the body
and parts proceeds, it shrinks at each end, so that when
near assuming the imago, a considerable cavity appears
both at the head and tail of the cocoon ^. At this period
of its existence, from the quantity of fluid included in the
puparium, the animal weighs usually considerably more
than it does when become a perfect insect \

The exterior integument or skin of pupae, which is usu-
ally lined with a very thin white pellicle, is of different
consistence in different orders. In the Coleoptera and
Hymenoptera it is, with a few exceptions, of a soft and
membranous texture; in the Lepidoptera (especially those
that are not defended by cocoons), and Diptera, it is more
rigid and harder, being either coriaceous or corneous.
Lepidopterous pup^, however, are not excluded from

a N. Diet. d'Hist. Nat. vii. 57. " De Geer ii. 106.
:^;^'^.Engl.Tr.U.3...xli./.. Co.p. Reau..

iv. t. XXV./. I.
" IbxdA. 144.

STATES OF INSECTS. 245

the last skin of the larvae with this hard covering. At
the moment of this change the envelope is nearly as soft
and membranous as in the order first mentioned. But
they are besides covered with a viscous fluid, which ap-
pears to ooze out, chiefly from under the wings, and
which very soon drying, forms the exterior hard shell >.
At first the antennae, wings, and legs, like those of Coleo-
ptera and Hymenoptera, can be each separated from the
body; and it is only after these parts have been glued to-
gether by the fluid just mentioned, which takes place in
less than twenty-four hours that they are immoveably
attached to the body of the pupa, as we usually see them.
In fact, the essential difference between incomplete and
obtected pupae seems to be, tliat in the former the limbs
and body are only covered each with a single membranous
integument, whereas in the latter they are besides glued
together by a substance which forms an additional an^l
harder envelope. It is not easy to explain the alteration
that takes place in the texture of the skin of such dipte-
rous pupae as retain the skin of the larva. In the latter
this is generally a transparent and very fine membrane :
yet the very same integument becomes to the pupa an
opaque and rigid case.

The surface of the skin of the greater number of pupse
is smooth, but in those of many Papilionidce it is rugose
and warty : this you may see, particularly in that of Pa-
pilio Machaon. In many of the hawkmoths {Sphinx L.)
it is covered with impressed puncta. In Attaais lo the
upper side of the channels that separate the intermediate
segments of the abdomen are curiously striated with trans-

' Reaum. i. ?,oh.

*• N. Diet. d'Hiit. Nat. ubi sup. 59.

246 STATES Ol- INSECTS.

verse striae, formed of very minute granuUv, the lower side
being transversely sulcated. In some few instances, as
in Arctia Salicis, Laria pudibunda and fascelma, the skin
of the pupa is clothed with hair : as is also that of He-
speria Bixce, according to Madame Merian^. De Geer
has described a little beetle under the name of TeJiehrio
lardarius {Latridius Latr., Corticaria Marsh.), the pupa
of which is beset with very fine hairs, terminating m
a spherical or oval button

ii. I shall include mider the same head both thejigure
or shape, and parts of pupae, as the latter in most kinds
are either the same or nearly the same as those of the
larva, or merely incasing those of the imago, so as not to
require that detailed notice that I judged necessary when
treating of the parts of larvae.

With regard to incomplete pupae, nothing further can
be said of their extremely various/o^wr^-, than that it has
a general resemblance to that of the perfect msect. The
head, trunk, abdomen, and their respective external or-
cans, are alike visible in both; but in the pupae, the latter,
instead of occupying their natural situation, are all closely
folded under the breast and abdomen : or, as m the case
of the long ovipositors of some Ichneumons, laid along the
back In a specimen of some coleopterous insect now
before me, the following is the order of the arrangement
of the parts :-The head is inflexed; themandibul* are
open • between them are seen the labium and labial palpi;
these'appear to cover and conceal the maxillae, and the
maxillary palpi extend on each side beyond them; the
Plate XVI. Fig. 14. N. Diet, d' Hist. Nat y\l 59
^ Ins. Sunnam. t. xliv. ^ De Geer v. 47- L n.f. 29-31.

STATES OF INSECTS.

247

antenna pass above the thighs of the two anterior pair
of legs, and then turning down over the breast between
them and tlie posterior legs, repose upon the base of the
winffs : which also are turned down between the inter-
mediate and posterior pair of legs, and rest upon the lat-
ter; the tibiae are bent in and folded upon the thigh,
and the tarsi turn outwards ^. In another coleopterous
species, the wings and elytra are placed under the hind-
legs. In Hymenopte7-ous pupae the antennae appear usu-
ally to lie between the legs In many Tipulcs the long
legs are bent into three folds in the pupae ; but the tarsi
are extended, and lie close to each other, the anterior
pair being the shortest In a specimen belonging to
this tribe in my cabmet, which I think contained Cteno-
cera pectiuicornis, the six leg-cases are of the same
length, exactly parallel and adjacent, and being annu-
lated wear the appearance of tracheae'*. These parts
have each their separate case, so that a pin may be intro-
duced between them and the body : which cases, as well
as the general envelope, are usually formed of a fine soft
transparent membrane ; but sometimes, as in the lady-
bird (Coccinella), the tortoise-beetle [Cassida), the crane-
fly ( Tipula), &c. it is harder and more opaque, so that
though it is usually easy for a practised Entomologist
from an examination of the pupa, particularly in the H^-
menoptera, to predict to what genus the insect to be dis-

" In the pupa of HydrojMliis piceus (Lesser L, n.f. 13, 14), the
;^rangement of the parts is nearly the same, but the tarsi are not re-
flexed.

^ Ibid.f. 9, 10. De Geer ii. t. xxxii./. 5. Reaum, v. t. xxxvi./. 14.
" Reaura. Ibid. t. ii./. 9.

* The legs of Tipula replicata L. are placed in a similar way. De
Geer vi. i. xx,/. 12. /.

248 STATICS OF INSECTS.

closed from them will belong, yet in these cases the organs
being not so conspicuous, a less experienced exammer
might be perplexed, and unable to come to a conclusion.

Although hymenopterous pupae have usually no parts
but what are afterwards seen in the perfect insect, this is
not the case with several coleopterous and dipterous ones,
which are furnished with various temporary appendages,
indispensable to them to bring about their final change,
or for other purposes. Thus, the pupa of the male ot
Lucanus Cerms has two short, jointed anal processes ^
That of Hydrophilus carahoides has a pedunculated lunu-
late one; and moreover, the sides of the abdominal seg-
ments, and the top of the thorax, are beset with hairs,
which are not seen in the perfect insect ^ The abdomen
of many, also, is armed with spines. That, the arrange-
xnent of whose organs I lately described, has a quadruple
series in the back of this part; viz. on each of the first five
segments, 3, 2, 2, 3. The five first ventral segments a^so
have on each side three spines; the inner are mcurved, the
intermediate nearly upright, and the outer one recurved.
These spines, except those of the innermost ventral series,
terminate in a bristle. In another coleopterous species the
back part of the head is armed with a pair of lateral spines
and that of the thorax with three processes, the external
ones armed with a single spine, and the intermediate one
with a pair. De Geer has figured the pupa of an Astlus,
the head of which is armed with eight spines-two ro-
bust ones in front, and three smaller ones, connected at
the base on each side. The abdominal segments, also
are fringed with spines ^ The abdomen of the pupa of
. Ros. 81 . " Ibid. t. 95. ^ De Geer ^d. i^37. /• xiv./. 8.

STATES OF JNSECrs.

24.9

Ctenocera pectinicornis is armed with several strong co-
nical spines, pointing mostly towards the tail, which is
likewise the case with that of Tipula lunata *. As the
above pupa9 are usually subterranean or subcortical, the
spines assist in pushing them out of the ground, &c.
The respiratory horns that proceed fi*om the thorax of
the pupae of many of the aquatic gnats will be noticed
in another place. Those of Corethra culiciformis and of
some other aquatic gnat-like DijJtera, have their anus
furnished with a pair of oars, or natatory laminae, by
which they rise to the surface ^.

The figure of ohtected pupse, or chrysalises, is more
uniform. They are commonly obtuse at the anterior ex-
tremity, and gradually contracted to a point at the poste-
rior, or tail. The outline usually inclines to a long oval
or an ellipse ; but in some, as Attaais lo and Luna, the
pupa is shorter and more spherical. In Geometra sam-
hucaria it represents an elongated cone, and in Hepialus
it is nearly cylindrical. In the buttei-fly tribe {Papilio L.)
the outline is fi-equently rendered angular by various pro-
tuberances.

In all these pupae may be distinguished the following
parts :—y?rs/f, the Head-case {Cephalo-theca\ or anterior
extremity ; secondly, the Trunk-case {Cyto-theca), or inter-
mediate part; and thirdly, the Ahdmien-case {Gastro-
theca).

1. The Head-case covers and protects the head of the
inclosed imago. From its sides behind proceed the an-

* Reaum. v. t. ii./, 7. The anal and ventral spines of Tipula re-
plicata are also remarkable. De Geer vi. /. xx./. 14.

" De Geer Ibid. 377. t. xxiii./. 8, 9. n. Reaum. v. 42. t. vi.f. 9. m n.

250 STATES OF INSECTS.

tennse-cases {Cera-theca); and before from the middle,
the tongue-case ( Glosso-theca). Just below the base of the
antenn£e-case you may discern the eye-cases {OjMalmo-
theca), surrounded on then- inner side by a crescent-
shaped laevigated piece, which may perhaps transmit
some light to the inclosed prisoner.

2. The Trunk-case, divided into the thorax, or upper
surface, extending from the head to the dorsal segments of
the abdomen, and consisting of three pieces, answering to
theprothorax, mesotJiorax, and metathorax of the perfect
msect: the first answering to the prothorax small, the
second covering the mesothorax very large, and the two
next representing the metathorax, at first appearing to
belong to the abdomen, but having no spiracle; and the
breast {pectus) or under-surface reachmg fi'om the head
to the ventral abdominal segments, from which proceed
the wing-cases {Ptero-theca) and leg-cases {Podo-theca\
which organs, with the antenna-cases and tongue-case,
entirely cover, or rather form, the breast. The arrange-
ment of the whole is as follows :-The wing-cases, which
are more or less triangular, and exhibit the larger ner-
vures of the wings, are a lateral continuation of the me-
sothorax, which turn downwards from the sides of the
breast, and cover, or replace, the three first ventral seg-
ments of the abdomen. The anten7ia-cases, united to the
anterior portion of the head just behind the eye-cases,
repose unmediately next to those of the wings running
parallel with their inner margin. Then follow the legs,
the tibiae forming an angle with the thigh, and the case
of the anterior pair being innermost, and representing the
breast-bone in the pupa. The tongue lies over the lore-

STATES OF INSECTS.

251

leo-s, except in the case of some sphinxes, which I shall
notice afterwards : so that the glosso-theca covers both
them and it.

3. The abdomen-case consists of ten segments when
viewed on the back, and of only six when viewed below ;
so that it might be said to have ten dorsal and six ven-
tral segments : but the fact is, that the place of the three
anterior ventral segments, or rather ventral portions of
the segments, (for they form complete rings without any
lateral suture,) are replaced by the wings and other or-
gans : in consequence of this, the fomth segment, which
is less covered than the three first, at its posterior margin
forms an annulus or rinff. In counting the abdominal
segments of a pupa, you must be careful not to include
the piece that represents the metathorax, which looks as
if it belonged to the abdomen ^. In the pupae of butte7-
Jlies you will discover evident traces of ten dorsal seg-
ments ; but in many moths, and some haisok-vioths, you
will perceive at first only eight, or even seven, but a closer
examination will enable you to discover the line that
marks out the others ; and if you divide the puparium
longitudinally, and inspect its internal surface, you will
see very visible sutures between them. The intermediate
segments are sometimes separated from each other and
the preceding and subsequent ones by deep channels.
In the pupa of Pajnlio Machaon there is one such chan-
nel between the third and fourth segments. In Bomhyx

The caterpillar consists of twelve segments (Lyonnet t. \.f. 4,5),
excluding the head ; on each of which, except the" 2d, 3d, and 12th,
there is a pair of spiracles. The chrysalis usually exliibits an analogy
to this structure, though the first, second, and last pair of spiracles
are more or less obsolete in most.

252 STATES OF INSECTS.

regalis the channel is between the sixth and seventh, and
in B. imperatoria there are three, namely, a channel be-
tween the third and fourth, and fourth and fifth, and fifth
and sixth segments. The way in which insects with an
exserted sting fold it in the pupa seems not to have been
noticed ; but from an observation of De Geer upon one
species of Ichneumon, it appears to be turned up over the
back of the abdomen ^

These little animals, thus swathed and banded, exhibit
no unapt representation of an Egyptian mummy; though
Lamarck applies the term Mumia to incomplete pupae ^
to which it seems less happily applicable.

Chrysalises, as to the modifications of theii- general
fio-ure, maybe conveniently divided into two great classes:
/rs^, those that have no angular projections, the anal
mucro of some excepted, on different parts of their body;
and secondly, those which have such projections. Each
of these classes affords variations in its pecuhar charac-
ters which require to be noticed.

1. The first of these are called angular pupae % and
are confined to \heButterJly or diurnal tribes. In some
the head projects into one short conical protuberance:
this you may see in the chrysalis of the common cabbage
butterfly {Pieris Brassicce), and others of the same ge-
nus ; in the brimstone-butterfly {Colias Rhamni'), and
in the beautiful purple emperor or high-flier {Apatura
Iris F. 0= though in this last it is not conspicuous. But

a De Geer ii. 847. t. xxix./. 7- a b.

Animaux sans Vertebres, iii. 287-
c N. Did. d'Hist. Nat. vii. 57.
d Sepp ii. t. If. 4. t. ii./. 4. t. iv./. 5.
« Plate XVI. Fig. 12.
f Plate XVI. Fig. 10.

STATES OF INSECTS.

253

the most remarkable instance of a single eminence from
the head is exhibited by the pupa of a tropical butterfly
{Morpho Idomeneus Latr.), figured by Madame Merian.
In this the head projects into a long incurved obtuse
horn In others the head is armed with two mucros,
or conical eminences. This is the case with the common
buttei-fly of the nettle [Vanessa Urticce F.''), and with that
of the beautiful Papilio Machaon ^. In these the promi-
nences are trigonal. These processes, which in some, as
in the peacock-butterfly ( Va^iessa lo), stand upright
and in others diverge [Papilio Machaon)^ form the eye-
cases of the included imago; and in their outer base
is planted the crescent-shaped piece I lately mentioned,
which seems intended to convey light into it. In many
the prothorax, besides a lateral angular projection, has
in the middle another triangular or trigonal one, some-
what resembling a Roman nose ; on each side of which
is a smaller elevated black point : so that it requires no
great stretch of imagination to find out in it a sort of re-
semblance to the human face, which, though not quite
so striking as honest Goedart figures it% is however very
considerable. In the pupa of Morpho Menelaus, figured
by Madame Merian this nasiform prominence of the
prothorax is extended into a long arched horn, reaching
to the middle of the abdomen. The pupa of the silver-
washed fritillary [Argynnis Paphia F.), and others of the
same genus, exhibit beneath this nasiform prominence

" Ins. Sttriiiavi, t. Ix. It is singular that the chrysalis of its congener,
Morpho Teticer,vihich. she figures t. xxiii., exhibits no such process.
The larvae also widely differ. Plate XVI. Fig. II.

' Sepp ii. t. m.f. 5. J Sepp i. t. viL/. 5.

* De Insectu,ed. Lister, t.]. ' Ins. Surinam. L liii.

254 STATES OF INSECTS.

a very deep depression, itself beset with one or more se-
ries of smaller angular elevations. Tbe back of the ab-
domen is often furnished with two rows of protuberances,
in some species larger, in others smaller- sometimes
sharp and conical, and sometimes fiat, and in some in-
stances resembling the fins of fishes ^ These bosses
usually decrease in size towards the tail.

2. The second kind of chrysalises are denommated
conical These, which include the crepuscular and noc-
turnal Lepidoptera, and the butterflies with onisciform
larvae, have no protuberances, and are less variable in
their form— their anterior extremity being almost con-
stantly oval and rounded, and their posterior conical and
acute. An exception to this form is met with in the pupa
of a moth long celebrated {Lasiocampa Pithyocampa)\
which has the head acute and the tail obtuse, and armed
with two points ^ Another occurs in that of the Cossus,
which has two points on the head, by which it makes
an opening in its cocoon: when it assumes the imago,
one of these is placed below the other ^ And some
few have the anterior end nearly flat instead of rounded
The pupa of the orange-tip butterfly {Pieris Cardammes)
seems intermediate between the angular and conical
kinds: it is somewhat boat-shaped, and distingmshed
bv a fusiform process from the head and tail ^. Other
modifications of the usual figure are met with, but are
for the most part so shght as not to require notice. One

• - See above. Vc. I. p. .31.

' Reaum. ii.l58. viii./.4,5.

f Lesser L. i. 160. note. t. "J- 19- . „ ,

z N. Diet. d'Hist. Nat. xxvi. 165. Reaum. i. o47. Rosel says
is present only in some individuals. I. n. 4/.

STATES OF INSECTS.

255

or two, however, should not be passed over. The pupae
of many hawk-moths {Sphinx L.) have the anterior piece
of the head-case elongated into a sort of cylindrical pro-
boscis, which is incurved beneath the breast : you will
find this formation in S. Convolvuli and Ligustri ^. In
some, as in a species figured by Madame Merian, that
feeds upon the A7ino7ia squamosa, it is rolled up like a
serpent in many folds In Noctua Linarice the tongue-
case turns upwards, and is prominent laterally beyond
the body"^. This singular appendage is one of those
beautiful instances of compensating contrivances, as Dr.
Paley calls them, which perpetually occur in the insect
tribes. The tongue of these hawk-moths is of very great
length, often three inches, while the pupa itself is scarcely
two ; it could not possibly, therefore, have been extended
at length, as it is in common cases, but is coiled up
within the above protuberance. When the tongue is but
a litde longer than the breast, the ordinary plan is ad-
hered to, but the apex of the breast projects a little over
the abdomen into a sort of nose, in which the end of the
tongue is contained. This conformation may be seen in
the pupa of Noctua Gamma, Verbasci, and many other
species. Sometimes, as in N. Linarice F., this projection
is recurved into a short horn.

I have before adverted to the adminicula or short spines
looking towards the anus, with which the dorsal segments
of the abdomen of some pupae are armed ; and by which,
when the time for their exclusion is arrived, they are
enabled to push themselves upwards or outwards from

" Plate XVI. Fig. 13. a. ^ Ins. Surinam, t. iii.

' De Geer ii. 433. U viii./. 4. t.

256 STATES OF INSECTS.

their several places of confinement : you will find these
in the pupa of the great goat-moth {Cossus lignipa-da);
and in the cylindrical pupa of the moth called the ghost
[Hepialus Humuli F.) there are two rows of sharp trian-
gular spines on the back of each segment. These are not
laid flat, but, as they do also in the Cossus, form an acute
angle with the body; which gives them greater power of
resistance. Those that constitute the row nearest the
base of the segment are longer than the anterior row,
the middle spines than the lateral ones. The first and
last segment are without them, and the last segment but
one has a sharp ventral transverse ridge, armed with
many sharp teeth ^ The abdominal spines lately men-
tioned, of semicomplete pupae, are also adminicula.

The tail of this description of pupae is in many m-
stances armed with a mucro, or sharp point, emerging
from its upper side. You will see this in most hawk-
moths. In the pupa of Hesperia Proteus the mucro is
truncate at the apex; m that of Bombyx impaata,-ia it is
long, and terminates in two diverging points. In the
majority of chrysalises of both descriptions the tail is
acute, and usually furnished with hooks of different kinds.
These are so various in shape and number, &c. tliat they
would probably afford good characters for discriminatmg
many allied species. In some there are but two or three,
in others five or six, in others they are more numerous ^
Sometimes they are quite straight ^ but most commonly
recurved, so as to form a hook. The hawk-moths, and a

a See above, Vol. II. p. 300. „u:„«,.
b This description was taken from a wanww in my own cabinet,
it is similarly described by De Geer i. 490^ /. vu./. ^.

c Plate XXIII. Fig. 8, 9. " Khemann Beitrage, 304.

STATES OF INSECTS. 257

few others, as Bomhyx Pini^ Cei-ura Vi/mla, Sec, have no
anal hooks whatever. Under this head I shall observe,
that in many conical pupae below the anal angle or mu-
cro, is the appearance of a vertical foramen or passage :
this is particularly conspicuous in Hepialus, in which it
is surmounted by a bifid ridge, and has under it a pair of
minute black tubercles.

A pretty accurate judgement of the division to which
the perfect insect when disclosed will belong, may usually
be formed from the figure of its chrysalis. All the angu--
lav ones, with scarcely any exception, inclose buttajlies.
The converse, however, does not hold ; for some that are
not angular, as those of Parnassim Apollo and Mne-
mosyne, and most of the Linnean Plebeii urhicolre, also
inclose flies of that description. With these exceptions,
all conical chrysalises give birth to moths or hawhnoths.
An idea even of the family or genus under which the
perfect insect will arrange, may be generally formed from
the figure of the chrysalis ; less distinctly, however, in
the conical or rounded, than in the angular kinds, in
which the prominences of the head and trunk, as before
explained, usually vary in different families. Even the
$ex of some moths may be judged from the pupae: those
of females being thicker; and those also of the females that
have no wings, or only die rudiments of them, will of
course vary somewhat from the ordinary form : but there
is a still more striking difference in that of Callimorpha?
vestita F., and others of the singular tribe before no^
ticedS called by the Germans Sacklrager (sack-bearers),
from the sack-like cases in which the larva resides. Tlie

" See above, Vol. I. 464.

VOL. III.

<J5!S STATES OF INSECTS.

females of these having not only no wings, but no anten-
nae, and legs not longer than those of the larva, their
pupa more resembles that of a dipterous than of a lepi-
dopterous insect, it being not easy to determine which is
the head and which the tail^

In these too we can often learn from the outline of the
wing-cases, whether the inhabitant of the chrysalis has
these organs indented or intire. If the former, the mar-
gins of these cases are sinuate, as in that of Vanessa
C. album; if the latter, they are hitire, as in Pieris Bras-
sicce. Even in conical pupae,— the size, the shape of the
antennae, which may be distinguished through the skin
that covers them, and slight modifications of the ordi-
form,-give indications of the genus of the included
insect sufficiently conclusive to a practised eye.

The true figure of coarctate pupae when they are ma-
ture, the parts of the future fly being very visible, and
each being included in a separate case^ is that of those
that belong to the incomplete division ; but as this is a
characternotcognizablewithoutdissection,itiscustomary,

in speaking of pupae of this description, to refer solely to
the shape of the exterior covering, which is in fact a cocoon
formed of the dried skin of the larva moulded into a dif-
ferent form. In this sense the figure of coarctate pupae is
extremely various. The majority of them are more or less
oval or elliptical, without any distinct parts, were it not
that they usually retain traces of the segments which com-
posed the larva's body Of this figure are the pupas of the
common cheese-maggot ^ and many othei- flies. Others

a Von Scheven in Naturf stk. xx. C)4. t.u.f. 4.

b Plate XVII. Fig. 2. I.esser L. t. ii. / 26.
Plate XVII. Fig. 1. Lesser L. L ii./ 24, 25. _
Whether M. Meigen has separated this fly generically from

STATES OF JNSECTS. 259

{Sepedon Latr.) have the pupa shaped like a boat. That
of Scava Pyrastri F. assumes the figure of a flask ; or,
according to Reaumur's more accurate comparison, of a
tear The tail of many of diese pupae, particularly of
aquatic species, is elongated into a sort of beak, either
simple or forked, or is beset with spines variously ar-
ranged. The pupa of Stratyomis Chamceleon, and other
allied species, difi^ers from all the rest of this subdivision
in retaining the exact form of the larva and hence con-
stitutes an exception to the general character of our se-
cond great Division.

iii. There is much less variety in die colour of pupae
than in that of larv£B. The majority of coleopterous and
hjinenopterous pupae are white, or whitish ; of lepido-
pterous and dipterous, brown of various shades, often
verging on black in the former and on red in the latter.
The angular lepidopterous ones, however, are more
gaily decorated. Some, Pieris Brasszcce, are of a greenish
yellow, marked with spots of black; others are of a uni-
form green, Apatura Iris, Pieris Cardamines; others, red-
dish, Vanessa C. album; others again red with black
spots, Ura7iia Leilus A still greater number shine as
though gilded Avith burnished gold — either applied m
partial streaks, Vanessa Cardui ; or covering the entire
surface, Va?iessa Urtica;. It was from this gilded appear-
ance in some obtected pupas that the terms Chrysalis and

others, I am not aware : in my catalogue it stands under the name of
Tyrophaga.
=■ Reauni. iii. 376. L xxxi./. 7.

Ibid. iv. 318. t. xxiii./ 1_'4. XXV./. 1.

Ins. Surinam, t. xxix.

2(30 STATKS OF IMSECTS.

Mrdia were applied to the whole. The alchemists mis-
took this for real gold; and referred to the case as an
aro-ument in favour of the transmutation of metals. But
Reaumur has satisfactorily shown, that in this instance
the old proverb is strictly applicable-" All is not gold
that glitters." He found that this appearance is owmg
to'the shining white membrane immediately below the
outer skin, which being of a transparent yellow gives a
golden tinge to the former ; in the same way that tuitoil,
when covered with a yellow varnish, assumes the metallic
appearance which we see in gilt leather. He mentions
too, that for the production of this effect-it is essential
that the inner membrane be moist: whence may be ex-
plained the disappearance of the gilding as soon as the
butterfly is ready to escape from the pupa. The shade
of colour in these gilded chrysalises is various : some are
of a rich yellow, like pure gold; others much paler; and
some nearly as white as silver. That of Hipparcha
Cassia F. is red with silver spots \

Thoucrh by far the greater number of the chrysalises
of moths^areof an uniform chestnut, brown, or black,-
a few are of other colours ; as that of Geometra almaria,
which is of a glaucous blue; of Noctua sponsa, lilac ; and
Noctua pacta, of a lovely blue, caused by a kind of
bloom, like that of a plum, spread upon a brown ground.
A similar bloom is found on that of Parnasszus Apollo,
and on the anterior pai't of that of Plaf^^pteria^ adtarra
Tnd siada in which last, Kliemann observed it to the

r ^.rinmn I xxxn. Lister imitated the gilding of TAn/W^^"*
, nu;S..fa S pi'e of a black gall in a strong defection of net-
'Z!-^^^^-^^--'-''^ when left on cuivpaper, he says,
wiu'exquisitely gild it.-Ray's LeUers, 87. 90.

STATES OF INSECTS. 261

be renewed when rubbed off'^. Many j)U])ae have the
sheatlis of the wings of a different colour from that of the
rest of tlie bod}' ; a few are variegated with paler streaks
or bands, as Clostera Anastomosis, which has two red
longitudinal stripes down its dark-brown back ; and that
of the common gooseberry and currant moth, which may
be found in every garden, has alternate rings of black
and yellow

A few pupae vary in their colour, as the painted lady-
h\ittQX^y{Va7iessaCardui\ some of which are light-brown
with gray streaks and golden dots, others wholly of a
golden yellow or brown, others of a light green

Almost all at their first assumption of the pupa state
have a different colour from that which they take a few
days afterwards. This last they retain until the disclo-
sure of the perfect insect ; except some that have trans-
parent skins, which a few days previously to this period
exhibit the colours of the included animal.

iv. There is as great variety in the length of the age
of Insects in their pupa as in their larva state. Some
species continue in it only tisoo or three days [Aleyrodes
Chelidonii 'LoXx., Tinea proletella 'L.) ; others, as many
iveeks, or months, or even yeajs. Each, however, has in
general a stated period, wdiich in ordinary circumstances
it neither much exceeds nor falls short of. The only
general rule that can be laid down is — that small pupas
continue in that state a shorter time than tliose of larger
bulk. Thus, amongst coleopterous genera, the more mi-
nute species of Curculio L. ; amongst the Hymenoptera,

Beilmge, 181. Sepp. pt. ii, iu/. 4. Rosel. I. i. 61. ii, 5.

252 STATES OF INSECTS.

t\iQlchneumonesminuti L.; amongst the Lejndoptera, the
subcutaneous tribes; and the majority of the Diptera,—
remain as pupae only a few days or weeks: while the
larger species in all these orders commonly exist in the
same state several months— many even upwards of /tc-o
years. There are, however, numerous exceptions to
ihis rule; for some large pupae are disclosed in a much
shorter time than some others not a twentieth part of
their bulk.

The reasons both of the rule and of the exceptions to
it are sufficiently obvious. And first, as to the rule :—
If you open a pupa soon after its assumption of that state,
you will find its interior filled with a milky fluid, m the
midst of which the rudiments of its future limbs and or-
gans, themselves almost as fluid, swim. Now the end to
be accomplished durmg the pupa's existence is, the gra-
dual evaporation of the watery parts of this fluid, and the
development of the organs of the inclosed animal by the
absorption and assimilation of the residuum. Reaumur,
by inclosing a pupa in a stopped glass tube, collected a
ouantity of clear and apparently of pure water, equal to
eight or ten large drops, Avhich had evaporated from it,
and was condensed against the sides of the tube, and it
was found to have lost an eighteenth part of its weight ^
It is plain, therefore, that this necessary transpiration,
other circumstances being alike, must take place sooner
in a small than in a large pupa. Next, as to the excep-
tions —Since the more speedy or more tardy evaporation
of fluids depends upon their exposure to a greater or less
degree of hent, we might d priori conclude, that pupa.

' Keauiii. i. 3Sr\

STATES OK INSECTS.

263

exposed to a high temperature would sooner attain nia^
turity, even though larger in bulk, than others exposed
to a low one ; — and this is the fact. The pupa of a large
moth, which has assumed that state in the early pai-t of
summer, will often disclose the perfect insect in twelve or
fourteen days; while that of an Ichneumon, not one hun-
dredth part of its size, that did not enter this state till
Jate in autumn, will not appear as a fly for seven or eight
months. But this is not the whole. The very same in-*-
sect, according as it has become a pupa at an earlier or
later period of the year, will at one time live but a few
weeks, at another several months, in that state. Thus,
if the caterpillar of Papilio Machaoti, one of those which
has annually a double brood, becomes a pupa in July,
the butterfly will appear in thirteen days : if not until
September, it will not make its appearance until the Jun6
following ; that is, not in less than Jihie or ten months :
and the case is the same with the pupae of Noctua Psiy
and of a vast number of other insects. To put beyond
all doubt the dependence of these remarkable variations
on temperature merely, it was only necessary that they
should be effected, as Lister long ago advised ^, by arti-
ficial means. This Reaumm* accomplished. In the
month of January he placed the chrysalises of several
moths and buttei-flies, v/hich would not naturally have
been disclosed until the following Mav, in a hothouse :
the result was, that the perfect insects made their appear-
ance in less than a fortnight, in the very depth of winter;
and by other numerous and varied experiments he ascer-
tained, that in this heated atmosphere five or six dayg

' Liblcr'r, Guclart. 1 21.

264 STATES or INSECTS.

hastened their maturity more than as many "weeks would
have done in the open air. Tlie disclosed insects were
in every respect perfect, and the females, after pairing,
laid their eggs, and then died, just as if they had not
been thus prematurely forced into existence. The con-
verse of this experiment equally succeeded:— by keeping
pupjE the whole summer in an icehouse, Reaumur caused
them to produce the fly one full year later than their or-
dinary period ^

This extraordinary fact leads us to a very singular and
unexpected conclusion — that we have the power of
lengthening or shortening the life of many insects at
pleasure; that we can cause one individual to live more
than twice as long as another of the same species, and
vice versa. Had Paracelsus made this discovery, it would
have led him to pursue his researches after the elixir of
immortality with redoubled confidence, and would have
supplied him with an argument for the possibility of pro-
longing the life of man beyond its usual term, which his
sceptical opponents would have found some difficulty in
rebutting. Even the logical Reaumur seems inclined to
infer from it, that this object of the alchemists was not so
chimerical as we are wont to conclude ^. He confesses,
however, if it were to be attained only by the same pro-
cess as ef}ects the extension of an insect's life— by pro-
longing its state of torpor and insensibility,— that few
would choose to enjoy it on such conditions. The maii
of pleasure, blunted by excess of use to all modern sti-
muli, might perhaps not object to a sleep of a hundred
years, in the hope of finding something new under the

" Reaiun. ii. 10 —

i- Ibid. 24.

STATES or INSECTS.

265

sun when he waked ; and an ardent astronomer would
probably conmiit himself with scientific joy to a repose as
long and as sound as that of the seven sleepers, for the
chance of viewing his predicted return of a comet, on
stepping out of his cave : but ordinary mortals would
consign themselves to the perils of so long a night with
reluctance, apprehending a fate no better than what be-
fel the magician, who ordered himself to be cut in small
pieces and put in pickle, with the expectation of becom-
ing young again

The duration, then, of an insect's existence in the
pupa state, depends upon its bulk, upon the temperature
to which it is exposed, and upon a combination of these
two circumstances. This experiment appears very sim-
ple. We seem to ourselves to have accomplished what is
so often undertaken in vain — to have found an entrance
into the cabinet of Nature, and to have made ourselves
masters of the contents of one of the pages of her sealed
and secret book. We deceive, ourselves, however : this
book, when it seems most legible, is often interlined with
sympathetic inks, if I may so speak, which require tests
unknown to us for their detection. If you lay up a con-
siderable number of the pupae of a moth now called Erio-
paster lanestris, the larva of which is not uncommon in
J une on the black-thorn, selected precisely of the same
size, and exposed to exactly the same temperature, the
greater number of them will disclose the perfect insect
in the February following ; some not till the February of
the year ensuing, and the remainder not before the same

' This is a legend of Virgil, of which an account is given in 77ie
Lay of the Lad Minstrel, Note xv. 12mo ed. 1822, p. 257.

266 STATES OF INSECTS.

month in the third year \ Mr. Jones of Chelsea, a most
acute lepidopterist, in one of his excursions captured a
female of Arctia mendica, another moth, which laid a
number of eggs, thirty-six of which produced caterpil-
lars : all these fed, spun their cocoons, and went into the
pupa state in the usual manner, but at the proper season
only twelve produced the fly. As this was no uncommon
circumstance, he concluded that the rest were dead : to
his great astonishment, however, in the next season twelve
more made their appearance ; and the following year the
remainder burst into life, equally perfect with the fore-
going ^ In this extraordinary result, which also occa-
sionally has been observed to take place in the emperor-
moth {Saturnia pavonia), the privet-hawkmoth {Sphinx
Ligustri), and that of the spurge {S. Euphorbice) % and
other species,-it is clear that something besides mere size
and temperature is concerned: for, these circumstances
being precisely alike, one pupa arrives at maturity m six
months, and another of the same brood requires between
two and three years. We can guess, that the end which
the All-wise Creator has in view, in causing this remark-
able difPerence, is the prevention of all possibihty of the
destruction of the species. Eriogaster la^iestris and Arc-
tia mendica, &c., for mstance, are doomed, for some rea-

a Haworth Lepidopt. Britann. i. 125. An instance is recorded in
Scriba's Journal, in which a pupa was not disclosed until the /o«r^
year. B. i. st. iii. 232. Pezold. 170.

b Marsham in Linn. Trans, x. 403. ^ „ .

c Meinecken found, that of several pupae of Saiurnut pavoma,
some kept all winter in a room heated daily by a stove and others
„rcoM chamber, some of both parcels appeared m March (none
earlier), and some of both had not appeared m July, though evidenUj
healthy. Naturf. viii. 143.

STATES or INSECTS.

267

son unknown to us to be disclosed from die pupa in
the cold and stormy mondis of February and March,
almost every day of which in certain years is so ungenial
that few insects could then survive exposure, much less
deposit their eggs and ensure the succession of a progeny.
Now, were all these to make their appearance in die per-
fect state in the same year, it might happen that the
whole race in a particular district would be destroyed.
But this possibility is effectually guarded against by the
beautiful provision under consideration, it being very im-
probable that three successive seasons should be through-
out unfavourable ; and without such occurrence, it is clear
diat some of the race of this moth will be preserved. In
the case of other moths, whose pupse though disclosed in
the summer are governed by the same rule, the prevention
of the exdnction of the species, by any extraordinary in-
crease in a particular year of their natural enemies, seems
the object in view But though the intention be thus
obvious, the means by which it is effected are impene-
trably concealed. What physiologist would not be puz-
zled with the eggs of a bird, of which one-third should
require for their hatching to be sat upon only a fortnight,
another third a month, and the remainder six weeks? Yet
this would be an anomaly exactly analogous to that ob-
served by Mr. Jones with respect to the pupae of A. men-
dica. Rammur found that when the skin of pupae was
varnished, so as to prevent absorption, the appearance of

* The exclusion of certain moths, &c. from the pupa is probably
regulated by the time their eggs require to be hatched, and the ap-
pearance of the leaves that constitute their appropriate food.

^ Mr. Marsham makes a similar observation in Linn. Trans., ubi
fnpr.

268 STATES OF INSECTS.

the fly happened nearly two months later than hi oi'di-
nary circumstances. Are we to conjecture that those of
the moth just mentioned, or of i). lanestris, that are lat-
est matured, from a greater degree of viscidity m tlie
fluid that forms them % have thicker and more imper-
vious skins than those disclosed at an earlier period .
Or are we to refer the difference to some unknown pe-
culiarity of organization ? On any supposition, the fact
remains equally wonderful ; and I know of none the illus-
tration of which is more worthy of the patient investiga-
tion of the physiologist.

As the period of maturity of the perfect insect is thus
in some cases not fixed even to years, and as in niany
it seems dependent upon such variable causes; nothing
appears more improbable than that it should ever be
so strictly determined, that even the week in which the
fly will leave its pupa-case can be pretty accurately pre-
dicted. Such, however, is the fact with regard to the
Ephemera so interestingly described by Reaumur the
ixiyriads of which that issue from the banks of the Seine
all appear in two or three days, somewhere between die
10th and 18th of the month of August^ in every year;
at which time the fishermen regularly expect them. A
like regularity attends the appearance of those descnbed
by Swammerdam, which every year, for three days about
the feast of St. John, issue in clouds from the Rhme -
Not only is the week fixed, but in several instances even

: ^h^ar^^^^^^^^^^ -"^'-"^^ to near the end

of thi montrit began on the 19th, .hen Reaumur ohscn cd ihe.n.

MX. 480. 488.

^ BiU. Nat. E. Transl. i. 103—.

STATES OF INSECTS.

269

tlie hour. The Ephemerae observed by Reaumur appear
at no other time than between eight and ten o'clock m
the evening ; and so unalterably is their exclusion fixed,
that neither cold nor rain can retard it. Between these
iiours, in the evenings on which they appear, you may
see them fill the air, but an hour before or after, you will
in vain look for one So also the silkworm-moth and
the havvkmoth of the evening primrose {Sphinx (Eno-
iherce) constantly break forth from the pupa at sunrise :
and the hawkmoth of the lime [Smerinthns Tilice) as cer-
tainly at noon ^. Schroeter states, that of sixteen speci-
mens of the death' s-head-hawkmoth [S. Atropos) which
he bred, evei'y one was disclosed between four and seven
o'clock in the afternoon

Before I conclude this head, I must observe, that after
a caterpillar or gnat has spun its cocoon, it sometimes
remains for a considerable period before it incloses itself
in the pupa-case, and casts off the form of a larva. Thus
the little pai'asite [Ichmmon glomei-atus L.) that destroys
the caterpillar of the common cabbage-butterfly, remains
a larva in its cocoon for many months, but it becomes a
perfect insect a few days after it has put on its pupa-
rium'*; and the caterpillars of the great goat-moth [Cos-
sus ligniperda), if they spin their cocoon in the autumn,
remain in it through the winter in the larva state;
whereas, if they inclose themselves in the month of June,
they assume tlie pupa, so as to appear as flies in three or
four weeks ^. It is not therefore easy to state precisely

Reaum. vi. 486. Brahm. 423. 421.

<= Natiirf. xxi. 75. J Reaum. ii. 423.

"= De Geer ii. 370. It is not certain, however, that De Geer did
not, in this instance, mistake the winter habitation of a lai-va for a

270 STATES OF INSECTS.

tlie age of those pupa? which are produced from larva?
that spin cocoons.

V. I have not much to say with regard to the sex of
pupse. The male is probably to be distinguished from
the female by being smaller; but in the first great divi-
sion of pupae, those which resemble the larvae, and are
locomotive, the female in numerous cases may be known
by the Ovipositor, or instrument for depositing her eggs
in their proper station: and the male also has his anal
instruments. Sometimes in this state the animal is so
matured, as to be capable of continuing its kind. I have
found the pupae both of a Gryllus L. and of a Cimex L.
in coitu.

vi. Though the pupae of the second great division are
usually not locomotive, yet I must not omit some notice
of their motions. As the legs of insects in this state are
folded within a common or partial integument, of course
none of the pupae now under consideration, with the ex-
ception of those of the Trichoptera order, can walk : co-
arctate ones are even incapable of the slightest motion,
and exhibit no symptom whatever of animation. Some
of those that are termed incomplete, however, and most
chrysalises, have the power of communicating to their
bodies a slight movement, extending more or less in dif-
ferent species, which is effected by the abdominal seg-
ments solely. Tlie latter, during the first twelve hours
of being pupae, when their skin is soft, frequently turn

cocoon intended to shelter the future chrysalis; since Lyonnet in-
ZZ us that they spin a habitation to pass the ^vmter in. Trmtc
Anatomique, &c. 9.

STATHS OF INSKCTS.

271

themselves, that the side on which they he may not be
flattened ; afterwards by far the majority merely wriggle
or twist their abdomen when touched, or in any way in-
commoded or disturbed. We learn from De Geer, that
the pupa of the ghost-moth {Hepialus Humuli), the co-
coon of which is more than twice the length of the chry-
salis, moves in it from one end to the other Bonnet
observed one of a moth (perhaps Lasioccmpa Qjiercus),
which alternately fixed itself at the top and bottom of its
spacious and obliquely-fixed cocoon ; descending slowly,
but ascending as quickly, and almost in the same manner,
as a chimney-sweeper in a chimney The pupa of the
weevil of the water-hemlock [Lixus paraplccticus) will
move from one end of the interior of a branch to another
by means of its adminicular aided by the motion of its
abdominal segments But the most locomotive of pu-
pae of the second division are those of gnats, and many
Tipulidans, which pass this state in the water. These
will move from the bottom.to the surface, and back again,
with great facility and velocity. I have.before mentioned
several other motions of pupas which I shall not repeat
here, by which they extricate themselves from their seve-
ral places of intermediate repose, before they leave the
puparium : if the imago were to be disclosed in the in-
terior of a tree, or in the earth, its wings would be ma-
terially injured in forcing its way out. The object of
several of the above motions may be to alarm insects that
might attack these defenceless beings. The twirling mo-
tion in particular, formerly noticed '^^ in some species, by

« De Geer i. 490. t. vii./. 3, 4. »> CEuv. ii. 1.

De Geer v. 329. a Vol. II. 300—.

« Vol. II. 298—.

0272 iTATES OF INSECTS.

causing a rustling against the sides of the cocoon, makes
a considerable noise-so singular in that of a red under-
wing-moth {Noctua pacta), that Rosel tells us, (who by
the by was more timid than becomes a philosopher,) that
the first time he heard it, he had nearly thrown away the
box that contained it, in his f.'ight ^

vii. We are next to consider The extrication of the per-
fect 'insect from the pupariim, or pupa-case, and from the
cocoon. The period when the pupa has attained matu-
rity and the inclosed insect is ready to burst the walls of
its prison, may be often ascertained. Just at this tmie
the colour frequently undergoes an alteration, the golden
or silver tint of the gilded chrysalises vanishes ; and those
which are transparent, usually permit the form and co-
lours of the insect within and the motions of their li bs
to be distinctly seen through them. In the Libelluhna
the eyes become more brilliant ^ The mature pupa3 of
the moth lately mentioned [Eriogaster lanesins) have a
particular swell of the abdominal segments, not apparent
in those that are to continue till another season, or
loncver ^ Those of the case-worms ( Trichoptera) push,
off "the grates from the cases which they have hitherto
inhabited, and swim about ^. Other signs and motions
doubtless predict the approach of this great change in
other species, which have not been recorded.

The mode in which insects make their way out of U.e
puparium differs in different orders. In ol^tected pup.,
ai^struccles of the included butterfly or moth first effect
Xitudinal slit down the middle of the thorax, where

* Reaum.vi. 407-

»T.iv.l01. d Dfi Geer ii. 566.

c Haworth Lepidopt. Bntann. i. 12/. l^^er

STATES OF INSECTS. 273

there is usually a suture for the purpose. The slit ra-
pidly extends along the head, and down the parts which
compose tlie breast, and the insect gradually withdraws
itself from its case. It is not, however, from the outer
skin merely that it has to disengage itself, but also from
a series of mner membranous cases, which separately in-
close the antennas, proboscis, feet, &c., as a glove does
the fingers ; and similar cases inclose the parts of the
perfect insect in pupre of all the other orders. This is
sometimes a work of difficulty, but ordinarily it is effected
with ease.

Incomplete and semicomplete pupae undergo nearly the
same process, save that in them the body is not swathed
up m a common case ; and therefore they have only to
liberate themselves from die partial cases that envelop the
several parts of their body.

In coarctate pupaa, as those of Muscidcc, Syrphidce,
CEstridcc, &c., the process is different. Their outer-case
is ordinarily more rigid and destitute of the sutures,
which in the former tribes so easily yield to a slight effort.
Yet in these, at the anterior end under which the head of
the fly lies, and from which it always issues, there is
commonly a sort of lid, joined by a very indistinct suture
to the rest, which can be pushed off, leaving a sufficient
opening for the egress of the insect. In the pupte of
many of this tribe tliis lid is composed of two semicir-
cular pieces, which can be separately removed. Many
species seem to be able to force off the lid of their pupa-
num, by merely pushing against it with theu- heads :
but the common flesh-fly and many other Muscidce, which
are perhaps top feeble to effect this, or whose puparia
are stronger than ordinary, are furnished with a very re-

VOL. III.

2*74. STATES or insects.

markable apparatus for this express and apparently sole
purpose. They are gifted with the power of introducing
air under the middle part of the head, to which the an-
tennae are fixed, and of inflating that part into a sort ot
membranous vesicle as big as the head itself; by the action
of which against the end of the pupa-casc, the lid is soon
forced off. So powerful is this singular lever, that it is
even sufficient to rupture the fibrous galls in which the
pup^ of the gay-winged Tcphritis Cardui^ are inclosed.
That it is designed by Creative Wisdom to answer this
sole purpose seems proved, fi'om its disappearmg soon
after the disclosure of the fly, whose head shortly becomes
all alike hard. Reaumur suspects that it may also be
intended to promote the circulation of the insect s fluids;
but to me his reasons appear not conclusive \ In one
instance a mode still more unexpected obtains. The i -
lustrious naturalist just named found that the fly whid
proceeded from one of the rat-tailed grubs iElo,lnlu.
Ltr.) had actually the power of completely reversmg i s
situation in its narrow case; and that it then employed its
tail in pushing off the lid, which other species remove by

means of their luais

The extrication of insects whose pup=B are above
m-ound, like tliose of butterflies, many beetles, flies, &c ,
Z comparatively a simple operation. But what, you «n
ask, becomes of Uiose species whose pup>E are concealed
ZL in the earth, or in the heart of the trees on which
their larv« have fed ? Of this you shall be informed.-
Coleopterous insects disclosed from pupa= thus cncum-

:rS~;'teReaa™.iv,Me.n.viii.
>^ Ibid. 472.

STATES OF INSECTS. 275

stanced, wait until their organs have acquired strength,
and their elytra are sufficiently hardened to protect tlieir
filmy wings from damage in forcing their way through
the earth or wood which covers them. Thus Oryctes nasi'
cornis, a rhinoceros beetle common on the Continent, is
a full vionth before it reaches the surface of the earth,
after quitting its puparium. But it is evident that no
delay would enable lepidopterous or dipterous insects,
which are witliout elytra, to make their way out of such
situations, without irreparable injury to their delicate
wings. Many of these, therefore, while still within the
hard case of the pupa, have the precaution, a few days
previously to their exclusion, to force themseflves up to
the surface of the earth, or, when they reside in the in-
terior of trees, to the entrance of their hole. This is ef-
fected by a successive wriggling of the abdominal seg-
ments, which in several species, of the Coleoptei'a^ Lepi-
doptera, and Diptcra orders, for this pui-pose, as has
been more than once observed*, are furnished with
sharp points {adminiada), admittmg a progressive, but
not a retrograde motion. The puparia of the great goat-
moth {Cossus ligniperda) may be often seen projecting
from orifices in willow-trees ; and those of the common
crane-fly ( Tipula oleracea) from the surface of the earth,
to which they have thus made their way from a depth of
several inches.

In all the preceding instances the exclusion of the per-
fect msect is complete, as soon as it has withdrawn itself
from the puparium. But to a very large number, even
after this is effected, the arduous task still remains of

» See above, p. 255—. and Vol. II. p. 301—.
T 2

276 STATES OF INSECTS.

piercing the cocoons of leaves, of thick silk, of tougli gum,
or even of wood, in which the pnpaj are incased. We
can readily conceive how the strong jaws of coleopterous
and hymenopterous species may be employed to release
them from their confinement. But what instruments can
be used for this purpose by moths in a state of great de-
bility, whose mouth has nothing hke jaws-merely a soft
membranous proboscis ? How shall the silkwo«th
(B, Mori)hvce its way through the close texture of asUken
ball, through which the finger could not be easily pushed.
Or the puss-moth {Cerura Vinula) pierce the waUs ot
its house of glue and wood, which scarcely yield to the
knife? You will not doubt that these difficulties have been
foreseen by Infinite Wisdom, and provided ag^mstby
• Infinite Powek. The egress of moths from their co-
coons is secured in two ways ;-either by some peculiarity
in the first construction of the cocoon by the caterpillar,
or by some process which the pupa or perfect msect is
instructed to perform. As examples of each, several cu-
rious instances may be cited.

The krva of the motli which about 1760 made such
havoc in the province of Angoumois in France becomes
1 pupa in tlJ mterior of the grain of wheat wh>ch .t has
excavated; but tl,e opening by which it first entered .
not bigger than a pin's point, and is quite msufhaent for
Leg^rssofthemoth. How, then is the latter to f<.ce
its way through die tough skin which surrounds .t? 1 he
larva, previously to assuming the pupa state gnaws out a
Mttle circular piece at that end of the grain where the head
of the future moth would lie, taking care
entirely. At this litUe door, wh.ch is sufiicient to pio
"ct it from intruders, the moth has but to push, whcu

STATES Ol' INSECTS.

277

falls clov.'n, and leaves a fi*ee passage for its exit. A
contrivance almost similar is adopted by a caterpillar
wliicli feeds in the interior of the heads of a species of
teazel [Dipsacus L.), for a minute and interesting history
of which we are indebted to Bonnet. This caterpillar
previously to its metamorphosis actually cuts a circular
opening in the head, sufficiently large for the egress of the
Tature moth ; but to secure this sally-port during its long
.sleep, it artfuDy closes it with fibres of the teazelj closely
but not strongly glued together ^ Another small cater-
pillar described by the same author, resides in the leaf of
an ash curiously rolled up into a cone, and then assumes
the pupa, which is inclosed in a silken cocoon, mgeni-
ously suspended by two threads hke a hammock in the
middle of its habitation, and of so slight a texture that
it presents no obstacle to the extrication of the moth.
It is the closely-joined sides of its leafy dwelling that form
a barrier, which, were it not for the precaution of the
larva, would be impenetrable to so small and weak an
animal. The Httle provident creature, before its change
to a pupa, gnaws in the leaf a round opening, taking
care not to cut through the exterior epidermis. This
door is to serve the moth for its exit, like that formed by
the wheat-caterpillar. But in proportion to its bulk its
verdant apartment is of considerable size. How then
shall the mothk now the exact place where its outlet has
been traced ? How, without a clue, shall it discover in
Its dark abode the precise circle which requires only a
inish to throw it down ? Even this is foreseen and pro-
vided against. Out of twenty positions in which its ham- ■

* Bonnet, (Euv, ii. 169.

278 STATES OF INSECTS.

mock mighthavebeen slung, the caterpillar has been di-
rected so to place it, that the silken cord tlmt suspends
the head is fastened close to the side of the door wh.eh ,t
has previously constructed ; and the moth, gu.ded by this
filum ariadneum, at once makes its way out of an apart-
ment which, but for this contrivance, might have been to
it a labyrinth as inextricable as that of Minos >.

The mode in which other caterpUlars provide for the.r
extrication, when become moths, from their silken co-
coons, is not less ingenious. Those "{f'l^ff'Xl
(of which I have lately said so much,) and others, form
oblong cocoons, which, viewed externally, you would at
the first glance assert were of one solid piece: but on
examining them more narrowly, you perceive one end of
them to be a distinct lid, of a size large enough to per-
mit the moth to issue out; and that it is kept m its place
by a few slight threads,- easily broken by pressure from
ImnK Afewpagesback' Imentioned a cocoon formed
bv the larva of Tortrix p asinana, of the f °f »
boat reversed, composed of two inclined walls lastened
together at the top and ends. In constructmg this cocoon
it firmly glues to each other the top and one end, so as to
tmaniinpermeable suture; but the other end. atwhich
the motlt is to issue, though externally tt seems as strong
Is the rest, is merely drawn close by a s ender thread or
two fastened on the inside, and easily broken from wuthm
And, what is partieular-ly singular in the construction of
d^s ingenious habitation, the sides formmg the end last
Sied, though originally requiring force to draw

. Bounce, 207. I. iv, m MxM. ccii.

« See above, p. 217-

STATES OF INSECTS.

279

them into their required position, become so elastic as to
close again when the moth has passed between them and
made her escape ; the cocoon preserving its usual shape,
even when deprived of its inhabitant ^. A similar cocoon
is constructed by another leaf-rolling caterpillar, that of
Tortrix chlorana ^. Many similar proofs of contrivance
in the construction of silken cocoons might be adduced,
but I shall confine myself to one more only — 1 mean that
lurnished by the flask-shaped brown one of Saiurnia Pa-
vonia, and some other moths. If you examine one of
these cocoons, which are common enough in some places
on the pear-tree or the willow, you will perceive that it
is generally of a solid tissue of layers of silk almost of
the texture of parchment; but at the narrow end, ox
that which may be compared to the neck of the flask,
that it is composed of a series of loosely-attached longi-
tudinal threads, converging, like so many bristles, to a
blunt point, in the middle of which is a circular opening
It is through this opening that the moth escapes. The
silk of its cocoon is of so strohg a texture and so closely
gummed, that had both ends been similarly closed, its
egress would have been impracticable ; it finds, however,
no difficulty in forcing its way through the aperture of a
sort of reversed funnel, formed of converging threads
that readily yield to pressure from within. But an ob-
jection will here probably strike you. You will ask, Is
not this facility of egress purchased at too d&'ar a rate?
Must not a chrysalis in an open cocoon be exposed to
the attacks of those ichneumons of which you have said
so much, and of numerous other enemies, which will find

' Bonnet, (Euvr. ii. 229. De Geer ii. 477.

<■ Sepp. iv. /. xi./. 8.

280 S'l'ATES or INSECTS.

admittance through this vaunted door ? Our caterpillar
would seem to have foreseen your dilemma ; at least, un-
der heavenly guidance, she has guarded against the dan-
ger as effectually as if she had. If you cut open the co-
coon longitudinally, you will see diat within the exterior
funnel-shaped end, at some distance she has framed a
second funnel, composed of a similar circular series ot
stiff" threads, which, proceeding from the sides of the co-
coon, converge also to a point, and form a sort of cone
exactly like the closed peristome of a moss ; or, to use a
more humble though not less apt illustration, like the
wires of certain mousetraps ^ In this dome not the
slightest opening is left, and from its arched structure it
is Impenetrable to the most violent efforts of any ma-
rauders from without; whilst it yields to the slightest
pressure from within, and allows the egress of the moth
with the utmost facility. When she has passed through
it, the elastic threads resume their former position, and
the empty cocoon presents just the same appearance as
one still inhabited. Rosel relates with amusing naivete
how this circumstance puzzled him the first time he wit-
nessed it: he could scarcely help thinking that there was
something supernatural in the appearance of one of these
fine moths in a box in which he had put a cocoon of
this kind, but in which he could not discover the slight-
est appearance of any insect having escaped from it, until
he slit it longitudinally ^ But from an observation of
Meinecken, it appears that these converging threads serve

a Plate XVlI.FiG. 5. N.B. Scpp's figin-o represents ihccMcrhr
r.nnel ; and this, which exhibits the cocoon divided long.tudn,ally,
the interior one, or dome.
Ros. I. iv. 31.

STATES OF INSECTS. 2Si

a double purpose ; being necessary to compress the ab-
domen of the moth as it emerges from the cocoon, which
forces the fluids to enter the nervures of the wings, and
give them their proper expansion. For he found, that
when the pupa is taken out of the cocoon, the moth is
disclosed at the proper time, but remains always crippled
in its wings; which never expand properly, unless the
abdomen be compressed with the finger and tliumb, so
as to imitate the natural operation ^.

I am next to give you some account of the second
mode in which the release of the perfect insect from
its cocoon is effected — that, namely, wherein its own
exertions chiefly accomplish the work. I shall from a
large number select only a few instances. The texture
of the cocoon of the silkworm-moth is uniform in every
part, and the layers of silk are equally thick at both
ends. The moth makes its way out by cutting or
breaking these threads at the end opposite to its head :
an operation which, as it destroys the continuity of
the silk, tliose who breed these insects are particularly
careful to guard agamst, by exposing the cocoon to
heat sufiicient to destroy the included pupa. The ques-
tion is — What instruments does the moth employ to
effect this? And this we are not able to answer satis-
factorily. Malpighi asserts that the animal first wets the
silk with a liquid calculated to chssolve the gum that
connects the threads, and then employs its lengthened
head to push them aside and make an opening*^. But, as
Reaumur has observed, besides that so obtuse a part as the
head of a moth is but ill fitted to act as a wedge, we find

' XaUirf. viii. 133.

Dc Bomhi/c, 29.

282

STATES OF INSECTS.

the threads not merely pushed to each side, but actually
cut asunder. He therefore infers diatthe eyes, which are
the only hard organs of the head, are the instruments by
which the threads are divided — their numerous minute
facets serving the purpose of a fine file It should be
observed, however, that Mr. Swayne confirms Malpighi's
assertion, that the silkworm does not cut, but merely
pushes aside, the threads of its cocoon ; and he informs
us that he has proved the fact, by unwinding a pierced
cocoon, the thread of which was entire ^ Yet Reau-
mur's correctness cannot be suspected: and he affirms,
that from observation there can scarcely be a doubt that
most of the threads are broken <= ; which is further con-
firmed in an account of the breeding of silk-worms pub-
Hshed in the American PMlosopJiical Transactions: in
which it is expressly stated, that cocoons out of which
the fly has escaped, cannot be wound Analogy, it
must be confessed, is against Reaumur's opinion; since
other kinds of silkworms make their escape by means of
s^fidd. Thus we are informed by Dr. Roxburgh, that
Attacus Paphia, when prepared to assume the imago,
discharges from its mouth a large quantity of liquid, with
which the upper end of the case is so perfectly softened,
as to enable the moth to work its way out in a ver^ short
space of time,— an operation which, he says, is always
performed in the night ^ Perhaps the two opinions may
be reconciled, by supposing the silkworm first to moisten
and then break the threads of its cocoon. In those
that are of a slighter texture, a mere push against the

^ Reaum. i. 624. " Trans, of the Socielt/ of Arts, vii. 131.

« Reauni. ubi swpr, ii. 351).

« Linn. Trans, vii. 35.

STATES OF INSECTS.

283

moistened end is probably sufiipient : and hence we find
in so many newly disclosed moths the hair in that part
wet, and closely pressed down If it be apparently
difficult for the silkworm-moth to effect an opening in its
cocoon, how much harder must seem the task of the
puss-moth {Cenira Vinula) to pierce the soUd walls of its
wood-thickened case ? Here the eyes are clearly incom-
petent; nor could any ordinary fluid assist their opera-
tion, for the gum which unites the ligneous particles is
indissoluble in aqueous menstrua. You begin to tremble
for the fate of the moth incarcerated in such an imper-
vious dungeon — ^but without cause : what an aqueous sol-
vent cannot effect, an acid is competent to ; and with a
bag of such acid our moth is furnished. The contents of
this she pours out as soon as she has forced her head
through the skin of the chrysalis, and upon the opposite
end of the cocoon. The acid instantly acts upon the
gum, loosens the cohesion of the grains of wood, and a
very gentle effort suffices to push down what was a mi-
nute ago so strong a barrier. How admirable and effec-
tual a provision ! But there is yet another marvel con-
nected with it. Ask a chemist, of what materials a vessel
ought to be to contain so potent an acid : he will reply,
— of glass. Yet om' moth has no glass recipient: her
bottle is a membranous bag ; but of so wonderful a fabric
as not to be acted up6n by a menstruum which a gum,
apparently of a resinous natiwe, is unable to resist ! This
fact can only be explained by the analogous insensibi-
lity of the stomach to the gastric juice, which in some
animals can dissolve bone, — and it is equally worthy of

» Peeolcl. 171.

284 STATES OF INSECTS.

admiration. In both cases, the vitahty of the membra-
nous or fleshy receptacle secures it from the action ot
the included fluid; but how— who shall explain?

Ordinarily it is the moth that breaks the cocoon ; but
in the goat-moth and many Toririces it is the pupa it-
self that performs the work, either wholly or partially.
The pupa of the former is for tliis purpose furnished
with sharp points upon the head, capable of effecting
this object ^ The locust-moth, another species of Cossus
(C. Bobinidc VecY), whose history has been admirably
detailed by Professor Peck, has a different process. " In
the silk-moth," -says he, " and all others which I have
had opportunity to observe, the chrysalis bm'sts vi the
cocoon, and the fluid which surroimded the new insect in
it escaping at the same time, so weakens or dissolves the
fibre and texture of the silk, that the moth is able to ex<
tricate itself, leaving the chrysalis behind it; but this is
not the manner in the locust-moth. After remaining till
all its parts are fully grown and it is ready to quit its
prison, a certain quantity of exercise is necessary, to
break the ligaments which attach the moth to the shell
of the chrysalis, and to loosen the folds of the abdomen.
In taking this exercise, it can only move the abdomen in
various directions : as one side of the rings is moved for-
ward, the hooks in the serrated lines above mentioned
(the adminicula) take hold of the silk, and prevent their
sliding back; the next flexure brings forward the oppo-
site sfde of the rings, which are prevented by the points
on that side from slipping back in the same manner, and
the chrysalis is forced out of the slightly woven extremity

* Lyoniict 16.

STATES OF INSECTS.

285

of the cocoon, and through the silk-lmetl cavity, till it is
protruded for about one-tliird of its length out of the
opening in the bark, and into the air

An exception to the genei'al rule — that the rupturing
of the cocoon is tlie business of the inclosed insect itself
— is met with amongst ants ; the workers of which not
only feed the young, but actually make an aperture in
their cocoons, cutting the threads with their mandibles
with admirable dexterity and patience, one by one, at
the time they are ready to emerge, tlie precise period for
M'hich these indefatigable nurses are well aware of, that
they may meet with no obstacle. Without this aid, the
young ant would be unable to force its way through the
strong and dense coating of silk that infolds it". And a
proceeding somewhat akin to this was observed by the
Hon. CaptaiA Percy, R.N., who himself related it tome.
Being fond of the study of insects, he was in the habit of
attending to their motions ; and in the beginnmg of Sep-
tember 1821 noticed those of a number of female T/'jmlrc,
probably T. oleracea L., busily engaged in depositing
their eggs amongst the roots of grass. While observing
these proceedings, he at the same time saw one quitting
its pupa-case, which had already by its own efforts go^t
its head, thorax, and anterior legs out of it. It was then
joined by two male flies; which, with their anal forceps
and posterior legs taking hold of the pupa-case, appeared
with their mouths and anterior legs to push the little pri-
soner upwards, moving her backwards and forwards:
and as they kept raising her, shifting their hold of the

Sovie Notice of the Insect which destroys the Locust-trees, 70
lliis Memoir is in some American periodical work, of which I have
not the title. H„,,e,. /-Wmv 82.

286 STATES OF INSECTS.

skin till she was entirely extricated, when they left her
to recover her strength by herself. Probably the extreme
length of the two pair of hind-legs of these animals may
render such assistance necessary for their extrication.

There remains yet to be explained under this head the
manner in which the perfect insect is excluded from cer-
tain aquatic pupffi; such as those Phryganca;, gnats,
and one of those Tipulidce that resemble gnats. These
pupffi (perhaps that they may be safe from the attack of
birds) are destined to remain during the greater part of
their existence in this state at the bottom of the water.
But it is obvious that if the perfect insects were there to
be disclosed, their wings would be wetted, and they would
be drowned. It is the provision by which this result is
obviated that now calls for your attention.

You have already been told that the larvae of Phry
cranes inclose themselves in cases of different materials,
open at each end K You have also learned, that m be-
coming pupae, they secure each end of their cases with a
aratino- of silled When that change has occurred, they
remai^motionless at the bottom of the water. Now how
are these pup^, encased in tubes of a greater specific
gravity than the surrounding fluid, to make their way to
The surface when the time has arrived for their becommg
denizens of the air? This they accomplish in the iollow-
in. manner :-The pupa is furnished with two strong
exterior moveable mandibuliform processes, and has the
power of moving its four anterior legs and antenna while
in the pupa-case. With these temporary jatos it makes
an opening in one of the silken doors of its case, forces its

a Vo. I. p. 467. bVol.II.p. 2G4.

STATES OF INSECTS.

287

way out at that end, and then by moving its legs, the
cases of which in some species are ciliated for this very
purpose, swims to the surface, where its skin splits, and
discloses the included insect. That these jaws are given
for the express and exclusive purpose of being thus ap-
plied, seems undeniable. The pupa eats nothing — they
are therefore in every other point of view supei-fluous.
They are given to it alone of all other similar pupaj, be-
cause unnecessary to all others ; and they are cast off
along with the rest of the puparium, the perfect insect
having no vestige of jaws

The gnat has to undergo its change on the surface of
the water — How is it to accomplish this without being
wetted ? In the pupa state they usually remain suspended
with the posterior end of the body turned downwards :
but when the period for its change is arrived, it stretches
it out upon the surface, above which its thorax is elevat-
ed. Scarcely has it been a moment in this position, than,
swelling out the interior and anterioi' parts of the thorax,
it causes it to split between the two respiratory horns.
Through this opening the anterior part of the gnat then
emerges. As soon as the head and trunk are disennrasred,
it proceeds with its labour, and gets out more and more;
elevating itself so as to appear in the puparium like a
mast in a boat. As it proceeds, the mast is more and
more elevated and lengthened, till it becomes nearly per-
pendicular—just as the mast of a boat is gradually raised
from a nearly horizontal to a vertical position : at this
period a very small portion of the abdomen remams in
the puparium. Neither its legs nor wings are of any use

^ Dc Geer ii. 519.

2gS STATES OF INSECTS.

in maintaining it in this position. The latter are too soft,
and, as it were, folded; and the former are stretched out
along the abdomen— the segments of this last part are the
only agents. The observer who sees how the little boat
gradually sinks, and how its margin approaches the wa-
ter, forgets the mischievous insect it contains, which at
another time he would crush without remorse, and be-
comes interested for its fate; especially should wind agi-
tate the water. A very little is sufficient to drive about
rapidly the little voyager, since it catches the wind in
some degree as a sail. If it should be upset, it would be
all over with it;— and numbers do thus perish. The gnat,
after having fixed itself thus perpendicularly, draws first
its two anterior legs out of their case, and moves them
forward, and next the two intermediate ones; then m-
clining itself towards the water, it rests its legs upon it,
for w^ter is to them a soil sufficiently firm and solid to
support them, although surcharged with the weight of
the msect's body. As soon as it is thus upon the water,
it is in safety; its wings unfold themselves and are dried,
and it flies away. AH this is the work of an instant S

The pupae of Chironomus plumosus proceed from those
red worm-like larvae so common throughout the summer
in tubs of rain-water, &c., described by Reaumur K
They are not inclosed in cases, but are of a greater spe-
cific gravity than the water at the bottom of which they
reside, until within a few hours of the exclusion of the
fly. They have the power of swimming, however; and
by moving the tail alternately backwards and forwards,
can slowly raise themselves to the top of the water. But

Rcauin. iv. 010—. _
" Ibi.i. V. :}0-. /• V./. 1-10. See above, \^. l^-l--

STATES OF INSECTS. 289

here occiu's a difficulty. For the extrication of the imago
it is necessary that they should remain quietly suspended
at the surface ; and moreover that the thorax, in which
the opening for its exit is to be made, should be at least
level with it : and this is precisely what takes place. If
you watch one of these pupae when it ascends from the
bottom, you will see that as soon as it has reached the top
it remains suspended there motionless ; and that its tho-
rax is the highest part of the body, and level with the
surface. Now the question is, in what way this is accom-
plished ? How can a pupa of greater specific gravity than
water, remain suspended without motion at its surface ?
and how can its thorax, which is at its heaviest end, be
kept uppermost?— By a most singular and beautiful con-
trivance, which I shall explain ; the more particularly
because it has escaped Reaumur, and, as far as I know,
all other entomological observers. The middle of the
back of the thorax has the property of repelling water-
apparently from being covered with some oily secretion.
Hence, as soon as the pupa has once forced this part of
its body above the surface, the water is seen to retreat
from it on all sides, leaving an oval space in the disk,
which is quite dry. Now though the specific gravity of
the pupa is greater than that of water, it is but so very
slightly greater, that the mere attraction of the air to the
dry part of the thorax, when once exposed to it, is sulfi-
cient to retam it at the surface; just as a small dry needle
swims under simUar circumstances. That this is a true
solution of the phaenomenon, I am convinced by the re-
sult of several experiments. If, when the pupa is sus-
pended at the surface, a drop of water be let fall upon
the dry portion of the thorax, it instantly sinks to the
VOL. in. u

290 STATES OF INSFXTS.

bottom,-the thorax, which belongs to the lieaviest half,
bemg the lowest ; and if the pupa be again brought to the
surface, so that the fluid is repeUed from its disk, it re-
mains suspended there without effort, as before. Just
previously to the exclusion of the fly, the dry part of the
thorax is seen to split in the middle. The air enters, and
forms a brilliant stratum resembling quicksilver, between
the body of the insect and its puparium ; and the former
pushina- forth its head and forelegs, like the gnat, rests
the latter upon the water, and in a few seconds extricates
itself wholly from its envelope.

Before I close this letter, I must state a fact connected
with the subject of it that deserves to be recorded. It is
a general rule, that one pupa-case incloses only on. insect ;
but Kleesius, a German entomologist, asserts that he
had once two specimens of Gastropacha quercifoha ^vo-
duced from one pupa; which was large, bemg Ml two
inches long, and one thick.

LETTER XXXII.

STATES OF INSECTS.

IMAGO STATE.

When the insect has quitted the exuviae of the pupa, it
has attamed the last stage of its existence. It is now
termed an Imago, or perfect insect; and is capable of
propagation.

Just after its exclusion, it is weak, soft, and languid :
all its parts are covered with moisture ; and, if a winged
insect, its wings have so little the appearance, either in
shape, size, or colour, which they are about to assume,
that it might be taken for a mutilated abortion, rather
than an animal in the most vigorous stage of life. If it
be a beetle, its elytra, instead of covering the back of the
abdomen, are folded over the breast : their substance is
soft and leathery, and their white colour exliibits ho
traces of the several tmts which are to adorn them. If
the insect be a buttei-fly or a moth, the wings, instead
of being of their subsequent amplitude, and variegated
and painted with a variety of hues and markings, are in
large species scarcely bigger than the little finger nail,
falling over the sides of the trunk, and of a dull muddy
colour, in which no distinct characters can be traced.

u 2

292

STATES or INSECTS.

If the exchuled insect be a bee or a fly, its whole skin is
wliite and looks fleshy, and quite unlike the coloured
hairy crust which it will turn to in an hour or two ; and
the wings, instead of being a thin, transparent, expand-
ed film, are contracted into a thick, opaque, wrinkled
mass.

These symptoms of debility and imperfection, how-
ever, in most cases speedily vanish. The insect, fixing
itself on the spoils of the pupa, or some other convenient
neighbouring support, first stretches out one organ, and
then another : the moisture of its skin evaporates, the
texture becomes firm, the colours come forth in all their
beauty; the hairs and scales assume their natural posi-
tion ; and the wings expanding, extend often to five or
six times their former size— exhibiting, as if by magic,
either the thin transparent membranes of the bee or fly,
or the painted and scaly films of the butterfly or moth,
or the coloured shells of the beetle. The proceedings
here described I witnessed very recently with regard to
a very interesting and beautiful butterfly, the only one of
its description that Britain has yet been ascertained to
produce— I mean Papilio Machaon. The pupa of this
bemg brought to me by a friend early in May this year
(1822), on the sixteenth of that month I had the pleasure
to see it leave its puparium. With great care I placed it
upon my arm, where it kept pacing about for the space of
more than an hour; when all its parts appearing conso-
lidated and developed, and the animal perfect in beauty,
I secured it, though not without great reluctance, for my
cabinet— it being the only living specimen of this fine fly
I had ever seen. To observe how gradual, and yet how
rapid, was the development of the parts and organs, and

STATES OF INSECTS. 293

particularly of the wings, and the perfect coming forth of
the colours and spots, as the sun gave vigour to it, was a
most interesting spectacle. At first it was unable to ele-
vate or even move its wings ; but in proportion as the
aerial or odier fluid was forced by the motions of its trunk
into their nervures, their numerous corrugations and folds
g]"adually yielded to the action, till they had gained their
greatest extent, and the film between all the nei-yures be-
came tense. The ocelli, and spots and bars, which ap-
peared at first as but germes or rudiments of what they
were to be, grew with the growing wing, and shone forth
upon its complete expansion in full magnitude and
beauty.

To understand more clearly the cause of tliis rapid
expansion and development of the wings, I have before
explained to you that these organs, though often exceed-
mgly thin, are always composed of two membranes, hav-
ing most commonly a number of hollow vessels, miscalled
nerves, running between them ^ These tubes, which,
after the French Entomologists, I would name nermres,
contribute as well to the development of the wings, as to
their subsequent tension. In the pupa, and commonly
afterwards, the two membranes composing the organs in
question do not touch each other's inner surface, as they
afterwards do: there is consequently a space between
them ; and being moist, and corrugated into a vast num-
ber of folds like those of a fan, but transverse as well as
longitudinal, and so minute as to be unperceptible to the
naked eye, the wings appear much thicker than in the
end. Now as soon as the insect is disclosed, a fluid enters

" See above, Vor.. II. p. 34G.

294 STATES OF INSECTS.

the tubes, and being impelled into their minutest ramifi-
cations, necessarily expands their folds ; for the nervures
themselves are folded, and as they gradually extend m
length with them, the moist membranes attached to them
are°also unfolded and extended. In proportion as this
takes place, the expanding membranes approach each
other, and at last, being dried by the action of the atmo-
sphere, become one. To promote this motion of the fluid,
seems the object of the agitations which the animal from
time to time gives to its unexpanded wings. That a kind
of circulation, or rather an injection of an aqueous fluid
into these organs, actually takes place, may be ascertained
by a very simple experiment. If you clip the wmgs of a
butterfly during the process of expansion, you will see
that the nervures are not only hollow, but that, however
dry and empty they may subsequently befomid, they at
that time actually contain such a fluid ^ Swammerdam,
who appears to have been the first physiologist that paid
attention to this subject, was of opinion that an aerifonn
as well as an aquiform fluid contributes to produce the
effect we are considering. He had observed that, if a
small portion be cut off from the wing of a bee, a fluid of
the latter kind exuded from its vessels in the form of
pellucid globules, becoming insensibly drops-which he
concluded proved the action of the latter; and he no-
ticed, also, that the wmgs were furnished with trachea,
which were at that time distended by the injected air;
whence he justly surmised, that the action of tl^ was
also of great importance to produce the expansion of the
wing^ And Jurine found that every nervure contams
Reauni. i. Men. uU. De Geer i. 73. Swamm. Blhl. Nat. u 184.
P Swamm. Ibid.

STATES OF INSECTS. 295

a trachea, whicli, proceeding from the interior of the
trunk in a serpentine direction, follows all the ramifica-
tion of the nervui'e, though it does not fill it ^. Though
Reaumur attributes the expansion of the wings chiefly to
an aqueous fluid, yet he suspects that the air on some
occasions conti'ibuted to it

The wings of the other tribes of insects probably differ
fi'om the Lepidoptera in the manner in which they are
folded. It should seem from Reaumur's description, that
those of some flies, instead of the straight transverse folds
of the former, have angular or zigzag folds ; which
equally shorten the wing. Many Hymenoptera have
wings without any nervures except the marginal. We
may conjecture that these are more simply folded, so as
to render their expansion more easy ; but even in tliese
wings there are often tracheas, which appear as spurious
nervures, and help to effect the purpose we are consi-
dering.

The operation of expandmg their wings, m by far the
larger number of insects, takes place gradually as de-
scribed above ; and,, according to their size, is ended in
five, ten, or fifteen minutes ; in some butterflies half an

* Jurinc Hi/menopt. 16.

•> iv. 342. Heroic! also attributes the rapid expansion of the wing
to the flow of an aqueous fluid, which he calls blood, into the ner-
vures, the orifices of which open into the breast. EntwicJcelungs.
dcr Schmetterl. 101. sect. 106.~M. Chabrier, in his admirable Essai
sur le Vol des Insectes {Mem. du Mim. 4ieme, ann. 325), having ob-
served a fluid in the interior of the nervures of the wings of insects,
thinks it probable that they can introduce it into them and withdraw
it at their pleasure : the object of which, he conjectures, is either to
strengthen them and facilitate their unfolding, or to vaiy the centre
of gravity in flight, and increase the intensit}' of the centrifugal force.

' Ibid. 340.

29G

STATES OF INSECTS.

hoiii-, in some even an hour. A few species, such as
Sphinx (EnotJiera F., require several hours, or even a
day, for this operation ; and, from the distance to which
they creep before it has taken place, a considerable de-
gree of motion seems requisite for causing the necessary
impulse of die expanding fluids In a few genera, how-
ever, as the gnat, the gnat-like Tipulidae, and the Ephe-
merae, this process is so rapid and instantaneous, that the
wings are scarcely disengaged from the wing-cases before
they are fully expanded and fit for flying. These genera
quit the pupa at the surface of the water, from which,
after resting upon it for a few moments, they take flight:
but this would evidently be impracticable, and immersion
in the fluid, and consequent death, would result, were not
the general rule in their case deviated from.

Some species of the last of these genera. Ephemera,
are distinguished by another peculiarity, unparalleled, as
far as is known, in the rest of the msect world. After be-
ing released from the puparium, and making use of their
expanded wings for flight, often to a considerable di-
stance, they have yet to undergo another metamorphosis.
They fix themselves by their claws in a vertical position,
upon some object, and withdraw every part of the body,
even the legs and wings, from a thin pellicle which has
inclosed them, as a glove does the fingers ; and so exacdy
do the exuviae, which remain attached to the spot where
the Ephemera disrobed itself, retain their former figure,
that I have more than once at first sight mistaken them
for the perfect insect. You can conceive without diffi-
culty how the body, and even legs, can be withdrawn

a Brahm. Inseh. ii. 423.

STATES OF INSECTS.

297

from tlieir cases ; but you must be puzzled to conjecture
how the wings, which seem as thin, as much expanded,
and as rigid as those of a fly, can admit of having any
sheatli stripped from them ; much less how tliey can be
withdrawn, as they are, through a small opening at the
base of the sheadi. The fact seems to be, that though
the outer covering is rigid, the wing inclosed in it, not-
witiistanding it is sometimes more than twenty-four hours
before the change ensues, is kept moist and pliable. In
proportion, therefore, as the insect disengages itself from
the anterior part of the skin, the interior or real wings
become contracted by a number of plaits into a form
nearly cylindrical, which readily admits of their being
pulled through the opening lately mentioned; and as
soon as the insect is released from its envelope, the plaits
unfold, and the wing returns to its former shape and di-
mensions. Thus our litde animal, having bid adieu to
its shirt and drawers, becomes, but in a very harmless
sense, a genuine descamisado and sanscidotte. It does
not seem improbable, that the pellicle we have been
speaking of is analogous to that which, in addition to the
outer skin, incloses the limbs of Lepidoptera, &c. in the
pupa state, but which they cast at the sr-me time with the
puparium, and leave adhering to it

The body of newly-disclosed insects commonly ap-
pears at first of its full size ; but tlie aphidivorous flies
{SyrpJms F. &c.), and some others, in about a quarter of
an hour after leaving the pupa become at least twice as
large as they were at their first appearance : this appa-
rent sudden growth, which is also noticed by Goedart,

^ Reaum. vi. 505—. /. xlvi./. 9. Comp. De Gee.

298 STATES or insects.

Remimiir found to depend upon the expansion of the
previously compressed segments of the animal by means
of the included air ^ Both in this instance and in that
of insects whose wings only require expansion, the size
of the imago often so greatly exceeds that of the pupa,
that we can scarcely believe our eyes that it should have
been included in so contracted a space. The pupa of
one of the beautiful lace-winged flies {Hemerohius Peiia)
is not so big as a small pea, yet the body of the fly is
nearly half an inch long, and covers, when its wings and
antennae are expanded, a surface of an inch square".

When the development of the perfect insect is com-
plete, and all its parts and organs have attained the re-
quisite firmness and solidity S it immediately begins to
exercise them in their intended functions; it walks,
runs, or flies in search of food ; or of the other sex of its
own species, if it be a male, that it may fulfill the great
end of its existence in this state— the propagation of its
kind. Previously to thus launching into the wide world,
or at least immediately afterwards, almost all insects dis-
charge from their intestines some drops of an excremen-
titious fluid, often transparent, and sometimes red. I
have before relr^ed to you the alarm that this last cir-
cumstance has now and then produced on the minds of
the ignorant and superstitious Whether this excre-

a r1™. iii. 378. Ibid. 385. ,

c Insects of the beetle tribe, especially such as undergo their me-
tamorphosis under ground, in the trunks of trees &c., are often a
considerable time after quitting the puparium before their organs
acQuire the requisite hardness to enable them to make their way
to the surflxce. Thus, the newly-disclosed imago of Celoma aurata
remains a fortnight under the earth, and that of Lucanns Ccrvus, ac-
cording to Riiscl, not less than three weeks.
«> See above, Yoi.. I. p. 34—,

STATES OF INSECTS.

299

ment is produced indifferently both by males and females
I cannot positively assert; but a circumstance related
by Jurine affords some ground for a suspicion that it
is peculiar to the latter. A specimen of a female of
Lasiocampa Riibi, when killed emitted some of this
fluid, which dropped upon the floor : this appeared to
attract the males to the apartment in which it happened,
and to the very spot — from whence it may be conjectured,
that the scent of the fluid brought them there, and that
the use of it is to bring the sexes together soon after ex^
elusion from the pupa

The colour, sculpture, and other peculiarities which
distinguish insects in this state I shall consider at large
in another letter, when I treat of their external parts and
organs. Under the present head I shall confine myself
to pointing out the characters by which the sexes of many
species are distinguished from each other; as likewise
the duration of their life in their perfect state ; together
with the circumstances on which this dm*ation depends.

I. Sexual Distinctions. The first general rule that
may be laid down under this section is, — That among
insects, contrary to what mostly occurs in vertebrate
animals, the size of the female is almost constantly larger
than that of the male. Even in the larva and pupa states,
a practised eye can judge, from their greater size, which
individuals will become females. There are, however,
some exceptions to this rule. Thus'amongst the Coleo-
ptera, the male Dynastidce^ remarkable for their horns,

* Jurine Hymenopi. 9. Note 1.

3Q0 STATES or INSECTS.

as you may see in D. Aloeus, Antcrm, Adaon, &c., as
likewise those of Lucanus, are larger than the unarmed
females ^ In the Neuroptera the female LibelluUda are
sometimes sensibly smaller, and never larger, than their
males'^. In the HymenopUra the male of the hive-bee,
but more particularly that of Anthidium manicatum and
other bees of that genus, is much more robust than the
other sex <=. In the Diptera, the same difference is ob-
servable in Sijrphus Bibesii, and some other aphidivorous
flies, and also in Scatophaga stercoraria\ And amongst
the apterous tribes, we are informed by De Geer that
the male o{ Argyroneta aqmiica, which builds an aerial
palace in the bosom of the waters % usually exceeds the
female in bulk ^ The reason of this rule seems in some
deoTee connected with the office of the female as a mo-
th^r, that sufficient space may be allowed for the vast
number of eggs she is destined to produce; and it is
when impregnation has taken place, and the eggs are
ready for extrusion, that the diff-erence is most sensible.
In the majority of cases this sexual disproportion is not
very considerable, but in some few it is enormous. Reau-
mur mentions a beetle, of which he intended to give the
history, the male of which is so small compared with the
female, that a bull not bigger than a sheep, or even a
hare, set by the side of the largest cow, would aptly con-
trast with them. This little beetle, he says, has wmgs

a Reaum. iv. 393. ^ee above, Vol. 1. 4/3-.

f De Geer vii. 304.

STATES or INSECTS. 301

and elytra, while the giant female has no vestige of either,
having the upper surface of its body naked and membra-
nous The species to which this illustrious Naturalist
here alludes, does not appear to have been ascertained.
The female of many gall-insects (Cocci) is so large in
comparison with the male, that the latter traverses her
back as an ample area for a walk But this is nothing
compared with the prodigious difference between the
sexes of Termesfaiale, and other species of white ants,
whose males are often many thousand times less than the
females, when the latter are distended with eggs Acci-
dental differences in the size of the sexes sometimes arise:
as when the female larva has, from any cause, been de-
prived of its proper supply of food, it will occasionally be
less than the male. De Geer has stated a circumstance
with respect to the Aphides that produce galls, that
should be mentioned under this head — the first, or mo-
ther female, is larger than any of her progeny ever be-
come ^.

The second observation that may be generally applied
to the sexes of insects is, that, size excepted, there is a
close resemblance between them in other respects. But
to this rule the exceptions are very numerous, and so im-
portant that it is necessary to specify examples of each
under distinct heads.

1. In some species the sexes are either partly or wholly
of a different colour. Thus, in the order Coleoptera, the
elytra of the male of Rhagiim meridiamm F. are testa-
ceous, and those of the female black. LeiHura l uhra of

" Rcaum.iv.30. Ibid. ^ iv./. 15.

' bee above, Vol. II. 36. Dc Geei iii. 25.

302 STATES OF INSECTS.

Linne, with red elytra, is the female of his L. iestacea,
in which they are testaceous. Cantharis dermestoidcs of
the same author is the other sex of his Mcloe March
one of which is chiefly testaceous, and the other black :
which seems to have so misled .Linne, that he placed
them hi different genera. One more instance m this
order the female of Cicindela campeslris, as was first ob-
served to me by our friend Sheppard, has a black dot on
each elytrum, not far from its base near the suture, which

the male has not.

Amongst the Orthoptera, the male Locusta F., as Pro-
fessor Lichtenstein has informed us % have a fenestrated
ocellus, which is not to be found in the other sex. I was
once attending to the proceedings of a Hemipterous spe-
cies, Pentatoma oleracea Latr., which I found in union :
the paired insects had white spots, but another mdividual
was standing by them, in which the spots were of a san-
<.uine hue. I mention this by the way only-the spots
in the prolific sexes being of the same colour : but might
not the red spotted one be a neuter? ^ . , •

The sexes o^ m^ny Lepidoptera likewise differ in then-
colour. I must single out a few from a great number of
mstances. The males Lyc^na Argus F have the up-
per surface of their anterior wings of a dark blue, while
in the female it is wholly brown. The wings of the for-
mer sex Hypogymna dispar are gray, clouded with
brown; but those of the latter are white, with black
spots. In the brimstone butterfly {Colias Mamm^v^Xnch
is one of the first that appear in the spring, tlie wmgs of
the male are yellow-of the female whitish. In the com-

Linn' Trans, iv. 54—,

STATES OF INSECTS. 503

mon orange-tip {Pieris Cardamines F.), 9ne sex has not
the orange tip to the upper wings: and, to name no more,
the male of Lyccena dispar, one of our rarest and most
beautiful butterflies, has only a single black spot in the
disk of its fulgid wings; while in the otlier sex, the pri-
mary pair have nine, and the secondary are black, with
a transverse orange fascia near the posterior margin.
But the most remarkable difference in this respect ob-
servable in the msects of tlie order in question, takes
place in a tribe, of which only one species is certainly
known to inhabit Britain — I mean the Papiliones Eqicites
of Linne: what he has called his Trojani and Achivi m
some instances have proved only different sexes of the
same species. Mr. MacLeay's rich cabinet affords a sin-
gular instance confirming this assertion;— a specimen of
a Papilio is divided longitudinally, the right hand side
being male, and tl>e left hand female. The former be-
longs to P. Polycaon, a Grecian, the latter to P. Lao^
docus, a Trojan. An instance of two Grecians thus united
is recorded in the Encyclopedic Methodiqne, as exhibited
in a specimen preserved in the Museum of Natural Hi-
story at Paris; which on the right hand side is P. Ulysses,
on the left P. Diomedes

In the Neuroptera, the Libelhdidcc are remarkable for
the differences of colour in the sexes. In the common
Lihclhda depressa, which you may see hawking over
every pool, the abdomen of the male is usually slate-
colour, while that of his partner is yellow, but with darker
side-spots. Reaumur, however, noticed some males that
were of the same colom- with the females". Schelver

' ix. 65. n. 110.

^ vi. 423.

301' STATES or INSECTS.

observed, when he put the skins of LibcUula dejjressa into
water, that the colours common to both sexes were in
the substance of the skin, and remained fixed ; while
those that were peculiar to one could be taken off with a
hair-pencil, and coloured the water: which therefore
were superficial, and, as it were, laid on \ The yellow
males, therefore, that Reaumur observed, were probably
such as had the superficial blue colour which distmguishes
them washed off. In Caleptenjx Virgo Leach, the for-
mer are of a lovely silky blue, and the latter green. In
Agrions F. nature sports infinitely in the colours of the
sexes.

In the order Hymenoptera there are often differences
equally great; the sexes of many of the Ichneumons and
Saw-flies are of quite different colours. The former tribe
Linne has divided into sections, from the white annulus
observable in the antennae of some, and from the colour
of their scutellum: but these are often merely sexual
characters^. The male of Anthopliora retusa Latr., a
kind of wild bee, is wholly black, the female wholly gray,
and of so very different an aspect that they were long
regarded as distinct species ; a mistake which has likewise
occurred with regard to the sexes of Osmia ccsnclescc?is,
another bee, of which the male has a bronzed and the
female a violet abdomen <=. The nose of male A?idrence
Latr. is often yellow, or white, as in A. hccmorrkoidaUs^
when that of the female is blacks The labrum also is often
of a different colour in the sexes, as in Ceratina Latr.

a Entomologische, &c. 224.
b De Geer ii. 847. 850. Jiirine HijmetwpL 100.
' Kirby Mon. Jlp. Angl. ii. "idQ. 264-
Ibid.n. 142-. H4, 147, 148, <S:c.

STATES OF INSECTS^

In the Diptei-a, Aptera^ Arachnida, &c., I am not aware
of any striking diflerence in the colours of the sexes.

ii. The sexes of insects vary (but more rarely than in
colour) in their sculpture also, and pubescence. Thus the
elytra of the females of many of the larger water-beetles
{Dytiscus) are deeply furrowed, while those of the males
are quite smooth and level ^ The thorax of the female
in several species of Colymbetes of the same tribe, as
C. Hybna-i and transversalis, on each side has several
tortuous impressed lines or scratches, like net-work,
which are not to be discovered m the male. Hyphydrus
gibbus Latr., which differs solely from H. ovalis {Dytis-
ais ovalis Illig.) in bemg thickly covered with minute
impressed puncta, is, from the observation of the Rev.
R. Sheppard, the other sex of this last, with which he
has taken it coupled; and it is by no means improbable
that Hydroporus picipes {Dytiscus pu7ictatus Marsh.) and
H. lineatus,—hetween which, as Gyllenhalhas justly ob-
served, the same difference only exists,— are in hke man-
ner sexual varieties. With respect to pubescejice, I have
not much to say. Another aquatic beetle, Acilius sulcatus
Leach, has not only its elytra sulcated, but the furrows
of these, and a transverse one of the thorax, are thickly
set with hair; whUe the male is smooth, and quite naked.
Particular care seems to have been taken by the Creator,
that when aU the above inhabitants of the water are paired,
the male should be able to fix himself so firmly, by means

» A remarkable anomalous exception to this rule sometimes oc-
curs in the female of B. margimlis, which has smooth elytra like the
male (Gyll. Ins Succ. i. 467-). I have this variety from the Rev.
Mr. Dalton, of Copgrovc, Yorkshire.

VOL. III. ^

306 STATES or INSECTS.

of his remarkable anterior tarsi, (which I shall afterwards
describe,) and these asperities, &c. in the upper surface
of his mate, as not to be displaced by the fluctuations of
that element, the reluctance of the coy female, or any
other slighter cause.

In a moth called the ghost {Hepialus HumuU), the
posterior tibia of the male is densely bearded, but not of
the female ^— Some Hymenoptera, as Ammophila Kirb.
and Stigmus Jurme, have the upper lip of the male clothed
with silver pile, while that of the female is not so orna-
mented. The legs of some bees are distinguished m the
sexes by a difference in their clothing. That observable
in those of the hive-bee has been before noticed \ In
Andrena of Latreille <= the posterior tibia of the female is
covered externally with a dense brush of hairs, for col-
lecting the pollen; and the posterior legs at their base
have a curled lock of hair-which are not to be found m
the male 'I. In Dasypoda, Melecta, AntJwphora, Centris,
Epicharis, &c. of the same author, the first joint of the
tarsus of the female, and in Xylocopa almost the whole
tarsus, is also similarly signalized from that of the oUer
sex. In Bomhcs, as in the hive-bee, the posterior tibiae
of the females and neuters are furnished with a basket of
hairs for carrying their pollen paste, which you will m
vain look for in the male ^. The latter, however, m some
species of this tribe are distinguished from the former by
the longer hairs of their legs, but not in the posterior
ones. Thus, in Anthophora retusa tlie first joints ot the

a De Geer i. <. vii./. H-

b See above, Vol. II. 125, Note".

e Melitta ** c. Kirby Man. Ap. Angl. i. HO

^ Ibid. t. iy.f. 10. a. b.f. 14. • rkd. t. xm./. 20. a.

STATES OF INSECTS. S07

intermediate tarsus are bearded internally with a thin
fringe of long hairs, and the first externally with a tri-
angular one of short ones at the apex : but what is most
remarkable, the last or unguicular jomt, which in al-
most every other bee is naked, is on both sides fringed
with long hairs ^. In that remarkable genus AcantJiopus
Ilh'g., of which the male only is known, the first and last
jomt of the intermediate tarsus have a dense external
brush of stiff hairs, which probably is also a sexual cha-
racter Another sexual kind of clothing is exhibited
by the females of those bees that have their labrum or
upper-hp mflexed {Megachile Latr.) ^. Their abdomen
is covered underneath with a brush of stiff hairs, involved
in which they carry the pollen they coDect. In the males
of some of this tribe, as of iW. Willughbiella, the first four
joints of the anterior tarsus on their inner side have a
long dense fringe of incurved hau-s": a circumstance
also to be found in the same sex of Xylocopa latipes, in
which the claw-joint also is bearded ^ In Andrena Latr.
the last dorsal segment of the abdomen of the same sex is
fi-mged, while that of the male is naked ^ In the humble-
bees {Bombus), the mandibles of the male are bearded
with curled hairs, while those of the females and neuters
are without them. Some bees, as Andrena and Halictus
Latr., have the anus of the female bearded, and that of the
male naked: in some Bambyces the reverse takes place.

» Kirby Mon. Ap. Angl. i. t. xi. Apis **. d. 2. «. fi.f. 18 a. b. c. d.
Loquebert Illustr. Icon. i. t. vi./. 6

f^^l ^P'' ** 1- «• **• 1- **• 2. «.

**. c. 2. fi. »* c. 2. y. **, c. 2 g

r K-t ' ^ Christ. Hyv^enopt. t. iv./. 3. b.

' Kirby Mon. Ap. Angl. i. t. iv. Melitta **. c./. \. a.

x 2

30& STATES OF INSECTS.

iii. With regard to the general shape of their body,
the male and female usually resemble each other: but
there are some exceptions to this rule. The male of the
hive-bee is much thicker and more clumsy than either
the female or the worker ; but in Halictus Latr. the males
are nearly cylindrical in shape, and very narrow; while
the other sex are oblong or ovate, especiaUy their abdo-
men: and in Andrena Latr. the former are much slen-
derer than the females, and of a more lanceolate shape.
But a still more striking difference in this respect be-
tween the sexes is exhibited by some species of the genus
Ptmus F., in which the male is long and slender, and the
female short and thick. This, in more than one instance,
has occasioned them to be mistaken for distinct insects :
thus, P. Lichenurn and P. similis, P. ovatus and P. tes-
taceus, of Mr. Marsham, are mere sexual varieties. But
the most entire abalienation of shape at present known,
is that which distinguishes the male from the female
Coccus; these are so completely dissimilar as scarcely to
have any part in common. In Bomb^jx vestita F., and
others of the same family, while the males are of the or-
dmary conformation of the order, the females are without
even the slightest rudiments of wings; they have no an-
tennae, the legs are extremely short, not longer than
those of the caterpillar; and the body is entn-ely desti-
tute of scales, so that they altogether assume tlie exact
appearance of hexapod larvae ^ A conformation nearly
similar takes place in the female of Tinea Lichenella; but
in this the feet are longer, and the anus is furnished with
a long retractile ovipositor ^.

a Scheven Naturfon. stk. xx. Go. t. n.f. 4. Compare Ibid. x. 101.
*> Reaum. iii. t. xv./. 18, 19.

STATES OF INSECTS. 309

iv. In many cases, the structure of particular _par/s and
organs of the body differs in the sexes. As the facts con-
nected with this part of our present subject are extremely
numerous and various, it will be convenient to subdivide
it, and consider the sexual characters that distinguish —
the Head, Trunk, and Abdomen of insects, and their se-
veral appendages.

1. The Head. This part in some females is consider-
ably larger than it is in the male. This is the case with
the ants, and several other Hymenoptera ; while in some
Andrence, as A. hcemorrhoidalis, and Staphylinidce, as
St. olens, that of the male is the largest. But in none is
the difference more conspicuous than m the stag-beetle
{Lnca?ius); in which genus the male not only exceeds the
female in the length of his mandibles, but also greatly
in the size and dimensions of his head. In the Apion
genus, the rostrum of die female is generally longer and
slenderer than that of her mate; and in Brentus, the
rostrum of one sex (probably the male) is long and fili-
form, while in the other it is thick and short. This is
particularly visible in B. dispar and maxillosiis % &c.

One of the most striking distinctions of the males in
this part of their body, are those threatening horns, usu-
ally hoUow, with which the heads of many of the male
lamellicorn insects and some others are armed, and which
give them some resemblance to many of the larger qua-
drupeds. Many are unicorns, and have their head armed
with only a single horn; which in some, as in Onjctes
Illig., Dynastes Endymion^, &c. is very short; in others,

Oliv. no. 8'J. Brcnlus, L If. l.b.r. i. n.f. 17. n. b.
OJiv. no. ;}. Scaiabceus, t. x\n\.f. ] 69.

310 STATES OF INSECTS.

very long, as in Dynastes Enema, Pan, Elephas \ In
one, agab, it is thick and robust; as in the clumsy Dy-
nastes Actceon^ : in another very slender, as in 07itho-
phagus spinifer^. With respect to its direction m Ele-
phastomus proboscideus MacLeay, it is horizontal and
straight; in Phaleria cornuta horizontal and broken, or
the apex turning outwards and forming an angle with the
base = ; in Dynastes Hercules horizontal, and recurved
at the' apex^; in D. Actceon, Elephas, and Typhon, re-
curving from the base. In Geotrupes dispar it is re-
curved, so that its pomt exactly coincides with that of
the porrected thoracic horn, with which it forms a kmd ot
forceps g. In Copris lunaris F. and Diaperis horrida, the
horn is nearly upright K In Onthophagus Xiphias it is di-
lated at the base, and reclming upon the thorax; and at
the apex attenuated, and bending forwards, or noddmg.
In Passalus cornutus itrises alittle, and then bends who ly
forwards. In Dynastes Milan, a most remarkable beetle,
it slopes backwards in a waving line ; and in Onthophagus
spinifer it is recurved and rechning.-In speaking of the
direction of the horn, you must recollect that it wiU vary
in proportion as the head varies from a horizontal posi-
tion: so that an upright horn will become -clmed or
reclined, as the head bends forwards or backwards; but
I speak of it as it appears when the head is horizontal.

. Oliv. 5ca.«6..M.xii./. 114. ^■^'/■^:-^^^^u2.
b Ibid. t. \.f. 33.

a Linn. Trans, vi. t. xix./. 12. t. xx./. 2.

^ Oliv. no. 57. Tenebrio, t. i.f. 2.

f Oliv. vbi supr. No. 3. t. If. 1-

g Oliv. no.3. i.iii./-20.a.

h Ibid. no. 65. Diaperis, 1. 1./. 3.

i Oliv. Scarabceus, t. xx./. 185.

STATES OF INSECTS.

811

Again, it varies in its teeth or branches. In Dynastes
Hercules it is armed with several teeth. In D. Elephas
and ActoEon it has only one large one at its upper base
In D. Milan it is serrated above. In D. Alcides, Tityus^
jEgeon, Cdp-is lunaris, &c. the horn is unarmed and sim-
ple at the apex. In D. Oromedon, Gedeon, Enema,
ActcBon and congeners, it is bifid. In some the horn is
at first a broad lamina or ridge, vk^hich terminates in two
branches, as in Onthophagus Vacca. In this the branches
are straight; but in another undescribed species in my
cabinet (O. Aries Kirby, MS.) they are first bent in-
wards, and then at the apex a little recurved : and in
D. dichotomus it is divided into two short branches, each
of which is bifid Other males emulate the bull, the
he-goat, or the stag, in having a pair of horns on their
head. In Onthophagus Tauj-us, these arms in their curva-
ture exactly resemble those of tlie first of these animals <=.
In Goliathuspidvemlentus, the straight, robust, diverging,
shai-p horns are not unlike those of some of the goat or
gazel tribe. I have a beautiful little specimen in my ca-
binet, (I believe collected by Mr. Abbott of Georgia,) in
which the horns have a lateral tooth, or short branch,
like those of a stag; and which I have therefore named
O. cervicornis. In O. Vacca, Camelus, &c. the horns are
very short, and nearly perpendicular. In the male of

' As Dynastes Actaon, Elephas, Typhon, &c. differ from Z>. Her-
cules, &c.,not only in their general habits, horns, &c., but also in
their maxiUae and labium,-the former in D.ActcBon being simple,
and m Z>. Hercules toothed, and the labium of the first bilobed at
tlie apex, and m the last entire and acute,— according to the modern
system they ought, therefore, to be considered as distinct genera
1 would restrict the name Dymstes to D. Hercules and its affinities-
JJ. ActcBon, &c. I would call Megasoma.

" Oliv. ScarabcEus, t. xvii./. 156. ^ Ibid. t. vui./. 63 .

312 STATES OF INSECTS.

Copris Midas, the two longer perpendicular horns have a
deep cavity between them, which, together with its black
colour, give it a most demoniac aspect ; so that you would
think it more aptly representative of a Beelzebub or Beel-
zehul than a Midas % or than Phameus Beelzehul MacL.
A similar cavity is between the occipital horns of Dia-
peris hccmorrhoidalh Payk. Some species of Ryncha^nus,
as R. Taurus, have a pair of long horns upon the rostrum
of the male, the rudiments only of which are to be traced
in the female ^ Other species go beyond any known
quadrupeds in the number of horns that arm then' heads.
ThvisDitomus cali/do7iiusBonem, belonging to Carabush.,
has three equal horns <=. The same number distinguishes
OntJiojphagus Bonasus ; but the intermediate one is very
short In Goliathus Polyphemus the middle horn, on the
contrary, is much longer and thicker than the lateral
ones, and forked at the apex; so that it looks as if it had
four of these weapons ^, A little Diaperh {D. virzdtpen-
nis F.), a native of Carolina, has four horns upon the
head of the male; namely, two long ones on the occiput,
and two short dentiform ones on the nose. In a species
nearly related to this, sent me by Professor Peck from
New England, there is a cavity between the two occipi-
tal horns. The same number distinguishes Onthophagus
quadricornis {Copris ¥.). The situation also of the
horns varies: In some it is in the middle of the head,
as Orvctes nasicornis, Copris lunaris, &c. : m others, as
in Onthophagus nuchico^-nis, Xiphias, &c. it is a process

^. Oliv. no. 83. 160. /. v../. 60. $-i'^-f-^^- ?; .. ^ .

nr 4 w f ^"2 Ibid, no. 6. t. vJi.y.

« Ibid. no. 36. t. n.J. I'J.

STATES OF INSECTS.

313

of the occqmt or luud-heaxl ; and in O. Oryx F. the two
horns proceed from the antet-ior part of tlie head. In
the otlier sex, hi insects the head of whose males is armed
with horns, they are usually replaced by mere tubercles,
or very short elevations, as you may see in the female of
Copris lunar is : or by transverse ridges, as in the Onlhu-
yhagi: or else the head is without arms, and quite smooth,
as in Diaperis^ Phaleria, &c. Wliat may be the use of
these extraordinary appendages, as well as those on the
thorax, and in some cases on the abdomen, (which I shall
mention afterwards), to the males, has not yet been ascer-
tained. Whether the individuals of this sex are more
exposed to the attack of birds and other enemies, in con-
setjuence of being more on the wing than the females,
and are dierefbre thus provided with numerous project-
ing points for defence, is a question worth considering
It is die only probable conjecture on the cui bono of these
arms that I can at j)resent make. Under this head I
ought to notice die remarkable membranous process of
an obovate shape, which like an umbrella covers die
head of Acheta umbraculata F. " Whether the sharp
curved horns which arm this part in another Acheta
figured by Stoll in an incumbent posture, with Uieir
point towards die mouUi, are a sexual distinction, we are
not informed, — probably they are.

The organs of the hea^l also present many sexual di-

See above, Vol. If, 224—.
Coquebert lUiutr. Icon, iii, xxi./. 2.
' Stoll Cii>alcs, I. xviii./. a jb c. Ci-Ulons t. iv, /. 16—18. Tliis sin-
gular animal, which was found by Mr. Patterson at the Cape of
Good Hope, is stated to be an a<iwal\c; and affords the only known
instance oi an Orlkopterous insect inhabiting the waters, 'Die Gri/l.
hlalpa iovei tlie vicinity of water.

314) STATES OF INSECTS.

stinctions. The upper lip (labrum) in Halictus Latr., a
tribe of wild bees, in the female is furnished with an in-
flexed appendage, which is not discoverable in that of
the male^; and the shape of this lip in Sphecodes Latr.
differs in the sexes ^ Perhaps the horn or tubercle ob-
servable on this part of some female NomadiB F. " may
be wanting in the male.

The under-lip {labium)— taken in a restricted sense for
that central part from which emerge the labial palpi, and
which is often considered as the mentum,— does not offer
any striking variations in the sexes. One, however, is
of importance, as it helps to prove which are the true
female Lucani. In the male the labium is emarginate,
in the female it is intire. This may be seen both in
i. Cerms and femoratus, and probably in other species.
The sculpture also is different, the lip being smooth in
the former and covered with excavated i^wncto in the lat-
ter. The tongue {lingua or ligula) of the sexes is usually
the' same; except in the hive-bee, in which that of the
neuters is longer than that of the male and female.

The upper-jaws [mandibula), however, often afford
striking sexual characters. The enormous protended
ones of the common stag-beetle {Lucanus Cervus) attract
the attention of the most incurious observer; and these
are now generally allowed to be of this description.
Geoffi'oy and Mr. Marsham, indeed, have asserted tliat
they have taken in coitu those with long mandibles : but
as these males are pugnacious, and attack each other with
great fury, as Mr. Sheppard informs me, it is not impro-
bable that these gentlemen may have mistaken a battle

>■ Jbid. **. a./. 4, 6. ^ Ibtd' Aprs . b. 190 •

STATES OF INSECTS.

315

for an amour : since not only have those with long man-
dibles been often taken united with those that have short
ones ^, but the same difference obtains in the sexes of
other species. This is particularly observable in Lucanus
Jemorattis, of which I received from Brazil many speci-
mens agreeing in every respect except in this, that one
had short and the other very long mandibles. These
organs vary in different specimens, as to the number of
their teeth and branches. They are singularly robust in
L, Alces ^\ but in none more threatening than in L. Ele-
phas in which they curve outwards and downwards.
In Mr. W. MacLeay's genus PJiolidotuSi they are almost
parallel to each other, and curve downwards ; in Lucanus
nebulosus Kirby, they assume a contrary direction''; as they
do likewise in Lamp-ima Latr.^ In Lucanus Capreolus
the points close over each other ^ In Lethrus F. in the
female, but not the male, the mandible is armed below with
a long incurved horn. In Lucanus serricornis they form
a complete forceps s. In Siagonium quadricorne Kirby
the mandible is furnished at its base with an exterior
horn, which is probably a sexual distinction. The male
of Synagris cornuta, a kind of wasp, is still more conspi-
cuous in this respect; for from the upper side of the base
of its straight slender mandibles proceed a pair of crooked,
decurved, tortuous, sharp horns, not only longer than

» By Rosel, by a friend of De Geer's, and by M. Marechal. De
Geer iv. 331—. Nouv. Diet. d'Hist. Nat. xviii. 225.

•> Oliv. no. i. Lucanus, t. n.f. 3. <= Ibid. t. iii./. 7.

Linn. Trans, xii. 410. t. xxuf. 12. ' Ibid. vi. 185. t. xx./. 1.
f Oliv. ubi supr. t. W.f. 4.
B Regne Animal, iii. t. xiii./. 3.
•> See Vol. I. Plate I. Fig. 3.

316 STATES OF INSECTS.

the mandible, but than the head itself ^ Many sexual
differences are observable in the mandibles of the va-
rious tribes of bees {AnthojpMla Latr.). Thus, in Colletes
Latr. the male mandible is more distinctly bidentate at
the apex than the female^: in Sphecodes Latr. and others,
the reverse of this takes place ^ Where these organs in
both sexes are toothed at the apex, they often vary in the
number of teeth. Thus, the female of Megachile centun-
cidaris Latr. has four teeth at the apex of its mandible,
while the male has only two^. In M. Willughhiella,
though the mandibles of both sexes have four teeth, yet
those of the male are sharp, and the two external ones
the longest; while those of his mate are obtuse, and all
nearly equal in length In Anthidium manicatum Latr.,
the former has only three teeth, while the latter has five^
The differences in this respect in the hive-bee have been
before noticed s ; those of the humble-bees {Bomhus Latr.)
are strikingly distinguished from each other; the female
mandible being very stout and wide, constricted in the
middle, and furrowed on its outer surface; and the male,
on the contrary, very slender at the apex, dilated at the
base, and without furrows ^.

Of all the organs of the head, none seem so little sub-
ject to sexual variation as the under-jaws {maxillce) \ I

=> Christ. Hymenopt. t. xviii./. 2.

b Mon. Aj). Angl. i. Melitta *. a. t. If. 5. ? . 7- (? •

c Ibid. Melitta **. a. t. ii.f. 6. ? . 7- <? • and **. b. I. m.f. 3. ? . 4. ^ ,

d Ibid.t.vnlf. 11. ? . 13.

e Ibid.i. t.vm.f. 9. ? . 10. 3.

' Ibid. Apis c. 2. /3. /. ix./. 6. ? . 7- <? .

« See above, Vol. II. 125. Note

h Mon. Ap. Angl. ubi siipr. i. xiii./. lo. ? . 14. <?.

' MacLeiiy Hot: Entomolog. 4—.

STATES OF INSECTS. 31?

can bring forward only one striking instance of it, and
some degree of doubt rests even upon that. In the genus
Neinognatha of Ilhger, the maxillae of the male are elon-
gated, narrow, setiform, and often involute or spiral, like
those of a bee or a butterfly. But that this is peculiar
to the males is at present only surmised ^. I possess se-
eral species of the genus, all of which are distinguished
by long maxillae ; though in some they are as long as
the bod)', and in others scarcel}' half that length. Gna-
thium Kirby is similarly characterized ^.

The maxillanj palpi occasionally differ in tlie sexes.
In Cerocoma those of the female are filiform, while the
two intermediate joints of those of the other sex are much
thicker than the first and the last =. In Hylcecetus and
Lymexylon^ those of the male are still more remarkable :
they are pendent, the last joint very large, and laciniated
so as to form a tuft ^. The female ones grow gradually
larger towards the end, but are not at all divided there
The palpi of male spiders are of a very different struc-
ture from those of the other sex, terminating in a very
complex incrassated piece, which has been supposed to
contain the organ of generation; but this, according
to Treviranus, is a mistaken idea— that oi-gan being, as
usual, to be found m the abdomen ^ In the common
gnat the palpi of the male are as long as the proboscis,
consist of five joints, and at the end are tufted with hairs;
while those of the female are scarcely one-fourth of its

* N. Did. d'Hist. Nat. xxii. 488;

^ Linn. Tram. xii. 425—. t. xxii./. 6. <^ Plate XXVI. Fig. 2.
Ibid. Fig. 3. « Qliv. no.xxv. Lymexijlon, t. l.f. 1.

De Geer vii.249-. t.xW.f. 20, 21. Treviranus Arachnid. 36—
i. u.f. 16. a be. iv./, 35— 3/.

318 STATES OF INSECTS.

length, have only three joints, and are not tufted. Whe-
ther the labial palpi in any genus differ in the sexes, I
cannot affirm with certainty : I have not, however, ob-
served any such variation in them.

I shall next mention some organs of the head, in which
the difference between the sexes is often very striking
and peculiar. You will readily conjecture that I am
speaking of the antenna. And here the advantage seems
wholly on the side of the males : since in them these
wonderful instruments of unknown sensations are not
only more complex, but usually more elegant, than
those of the other sex. You will pardon me, therefore,
if I enlarge a little more than ordinary upon a subject so
full of interest, and say something upon the differences
observable between the sexes-in the shape, magnitude
and length, number of articulations, ramification and
plumage, and individual joints of their antennae.

With reo-ard to their shape, variations are sometimes
observable between the antennae of the sexes; but this
principally occurs in the Hymenopte^-a order For m-
stance, those of Chelostoma ma^rillosa, a smaU bee that
deposits its eggs in little holes in posts and rails, are cla-
Je in the female and filiform in the male -a cnxunr-
stance that distinguishes in some degree those oi Sphe-
codes, Halictus, and Andrena of LatreiUe, three other
.enera of wild-bees ^ In Dinetus Jur. the male antenna
are moniliform at the base, and filiform at die apex ; the
female, on the contrary, are entirely filiform ^

^ Ibid. Melitta **. a. t, n.f. 8. ? • 9. <? • ana J
7. ^.**.c.<.iv./. 11. 6.
' Jurine Hymenopt. <. 11./. 2.

STATES OF INSECTS.

319

The antennae of the sexes also sometimes differ in
magnitude and length. This is the case in the three ge-
nera of wild bees just mentioned ; those of the female be-
ing thicker than those of the male, while these last are
longer than the former. But in this tribe the males of
the Fabrician genus Eucei-a are most remarkable for their
long antennas ^ With regard to the different length of
these organs in the sexes, no insects are more distinguished
than some species of the capricorn-beetles {Ceramhjx L.).
In Lamia Sutor the male antennae are twice the length of
the female ; and in another Brazilian species in my cabi-
net, related to L. annulata {Stenocorus R), they are thrice
their length. Some of the Anthribi F. approach the
Cerambycidce, not only in some other characters, but also
in this circumstance :— thus the antennae of A. albinus, a
native of Britain, are vastly longer in the male than in
the female; and in A. cinereus {Macrocephalus Oliv.)'',
which I suspect to be of the former sex, they are as long
nearly as is usual in the tribe just named, called in France
capricorn-beetles.

I may here observe, that sometimes in the sexes a dif-
ference is also to be found in the direction or flexure of
their antennae. Thus in Scolia F., Pepsis F. &c., in the
males the antennae are nearly straight, but in the females
convolute or subspiral. The reverse of this takes place
in Epipone spinipes, a kind of wasp, and its affinities; and
Systropha lUig., a kind of bee : for in these the male an-
tenna is convolute at the apex % and the female straight.
In the various tribes of bees {Anthophila Latr.), these

Mon. Ap. Angl. i. Apis **.A.\.t. x.f. 7.
^ Oliv. no. 80. Macroce2)haliis, t. If. 2.
" Latr. Gen. Cnist. et Tm. iv. 156.

820 STATES OF INSECTS*

organs in the latter are what is denominated hrolcen, the
m^in body of the antenna forming an angle with the first
joints : but in the former this does not take place.

The antennee of the sexes do not always agree in tlie
number of joints. In the bees, and many other Hijmeno-
ptera, the male has one more joint than the female; as is
the case also in (Edemera notata {Cantliaris acwte Marsh.).
In Pteronus Laricis, a kind of saw-fly, the latter has only
sixteen joints in its antennae, while the former has twenty-
four ^ ' In Bhipicera marginata, a beetle, the beautiful
antennae of the male consist of thirty-two joints, while
the female has no more than eleven ! In Chelomcs Jur.
the male, on the contrary, has the smaUest number of
joints, namely sixteen; while the female has twenty-
five". ■ .,11-

In nothing do the sexes differ more materially than in
the ramtyication of these organs, and their ^.Z^^mag.. By
• attending to this, you may often detect the sexes in an
mstant; since the antennae of the males in numerous in-
stances are much more complex than those of the females
For what end the Creator has so distinguished them is not
quite clear ; but most probably this complex structure is
for the purpose of receiving from the atmosphere mforma-
tion of the station of the female. A tendency to branc img
will be found m the antennae of some males, in tribes where
these organs are usually perfectly simple in both sexes.
Thus in the male of Chelostoma maj:iUosa,— mistaken lor
anotlw species by Linne, which he names Api. f ~
,,V^the intermediate joints on their mner side project
int^ anangle^; andthose of the samesex of thecommon

, t ^\ f H " Ibid.

» Jurine Hpncnopt. 61. t. vi./. »•

c Mon. Ap. A»gl. i. /. ix. /Vpis * ' • c- 2. y-J- ^-

STATES OF INSECTS.

321

hornet, by means of a central sinus, have two obtuse
teeth on each. With regard to more direct ramifica-
tions, some male antennae terminate in a fork, or two
branches. This is the case with Hylotoma furcata Latr.,
a saw-fly and the peacock-louse {Nirmus Pavonis
Herm.) Others, again, have three lateral branches,
as in Eulophus Geoffr. a little parasite, the male anten-
nae of which send forth a hairy external and rather long
branch, from the base of the fourth, fifth, and sixth
joints <=. In Elater fabellicornis L., the eight last joints
are flabellate, or elongated and flat, resembling the sticks
of a fan in the male '•j in the female they are shorter, and
more properly may take their denomination from the
teeth of a comb. In Lainjpyris Latreillii Kirby, the an-
tennae of the former are flabellate on both sides, while
those of the latter are little more than serrate \ These
organs are extremely beautiful in the males of the RJii~
picerce of Latreille. In R. marginata K. they consist of
tliirty-two joints, from thirty of which issues a branch,
the first very short, but the rest gradually increasmg in
length as they approach the middle of the antenna; then
gradually decreasing to the end, so as to represent an
expanded fan But in none are they altogether so re-
markable as in those moths that Liime denominates
Bombyces Attaci, and some others. In these, in the males,
these organs in their contour are lanceolate, and every
joint is furnished with a couple of parallel equal branches
on each side K In the females these branches are shorter

"PiATEXI.Fio.ig. " Plate V. Fig. 3.

* Pi-ate XI. Fig. 18. - Ibid. Fig. 17.

J Plate XXV. Fig. 11. Linn. Tmns.xn. t. xxi.f. 4. a.

" PLATJiXXV.FlG.22.

VOL. nr. V

322 STATES OF INSECTS.

on the whole, and alternately one long and one short; but
in some, as Saturnia Pavonia, there is only one sliort
branch or tooth on each joint in this sex \ In Bomhyx re-
galis &c. only the first part of the antenna is so branched ;
and those of the female are setaceous and without branches.
In B. versicolor, &c. there is only one branch from each
side on every joint ; those of the female being much
shorter than those of the male. The latter sex of Ptero-
nus Laricis Jur., a saw-fly, afford an example of a dif-
ferent structure, the antennae on one side sending forth
a branch from every joint but the two first; but on the
other side, the nine or ten last joints also are without a
branch. The female antenna is serrated In another
of this tribe, Pterygopterm ductus Klug, the male an-
tenna resembles a single-toothed comb, being branched
only on one side : that of the female, like the former in-
stance, is serrated <=. Whether the remarkable antenna
that distinguish the known individuals of the genus Phen-
godes {Lcmpyrisphmosay.) is a sexual character has
tiotbeen ascertained; but it is not improbable that it
may be, as in other Lampyrid^. A pair of dehcate
flexile and almost convolute plumose branches proceeds
from the apex of each joint except the basal ones, which
have something the air of cirri, and give a more than
usual degree of lightness and elegance to these organs
Other antenna, especially in the Diptera order, assume
an appearance o^plumcs-not from the branches that pro-
ceed from them, but from the fine long hairs that Deset
and adorn them. These are universally indications of the

» De Geer i. t xix f. 11. 13. " Jnrine Hj,menopL t. vi./. 8.
c Plate XXV. Fig. 25, 26. Ibid. Fic. 4.

STATES OF INSECTS.

S2S

male sex, those of the females being generally compa-
ratively naked. If you take the common gnat, you will
find that the antennae of one individual are thickly fringed
on each side, and tufted at the end with fine long hairs,
while in the other only four or five placed at intervals in
a whorl are to be perceived ^. In Chironomus Meig., a
kind of Tipula L., resembling a gnat, the male antennae
are beset on all sides with the finest hairs, and resemble
a beautiful plumed while the females to the imarmed
eye appear naked. Even in some Hymenoptera, the an-
tennae of the males are thus feathered, in a less, degree :
for instance, in Hylotoma Latr. Whether the tufts
and fringes which ornament, in a remarkable manner,
the antennae of many CeramhycidcB ^, are sexual charac-
ters, is not certainly known.

We are now to consider other sexual differences in
these organs, resulting from the size or configuration of
one or more individual <joints. To begin with the first
joint, or scapus. In many of the Hymenoptera^ particu-
larly the Anthophila Latr., this is elongated, and the re-
maining joints form an angle with it in the females : while
in the other sex it is much shorter, and in the same line
with the rest of the antennae ; and in Hylceus dilatatns
{Melifta dilatata Kirby) the first joint in the male is di-
lated and shaped something like a patella ^ In Mala-
chius bipustulatus, &c. the sex just mentioned is pecu-
liarly distinguished by a white excrescence on the first

^ Reaum. iv. t. xl.f.2. aa. S.t. xxxix./ 3. ? . In the last the
hairs are too conspicuous.

' ^l ATE XII. Fig. 24. <■ Jm-ine H.jmniopt. t. vi /. 3

Plate XII. Fig. 25, 2G. XXV. Fig. 17, 32!
' Ihiil. Fig. 12.

324. STATES OF INSECTS.

four joints of the organs in question, most conspicuous
in the second and fourth. The antennie of male Cero-
camce are not very different". Mr. Marsham has de-
scribed a little Haltica under the name of Chrysomela
nodicornis, from a peculiarity of the same sex not to be
found in the other. The fourth joint is very large and
obtriangular; in the female it is merely longer than the
rest. In H. Brassica and quadripustulata the fifth jomt
is larger and longer than all but the first in the male, m
their females it is only longer. In some moths {Hermi-
nia Latr., Cramhus F.) there is also a knot in the middle
of the male antennae''. In Noterus, a water-beetle, the
six intermediate joints are thicker than the rest, begin-
ning from the fourth, and the last but one ends mternally
in a" truncated tooth. The fifth and two following joints
in the male antennae of Meloe are larger than the rest,
which distinguishes them, as well as a remarkable bend
observable at that part

Variations of the kind we are considering are also ob-
servable in the clava, or knob, in which antenna often
terminate. You have doubtless observed that the la-
mellated clava of the antenna of the common cockchafer
is much longer and more conspicuous in some mdmduals
than in others-the long clava belongs to the male . In
another species, M. Fidlo, that of this sex is nme or ten
times the length of that of the other. In Colymbetes
serricornis, a water-beetle, the male has a serrated clava
of four joints. In Dorcatoma dresdensis % and also Eno-
plium damicorne, two beetles, it is nearly branched m the

= PtATE XII. Fig. 7. - Pi.atkXXV.Fio.1.

• Ibid. Fig. 21.

STATES OF INSECTS.

^25

male, but much less so in the female. In a little destruc-
tive beetle, common m our houses {Altagenus Pellio\
in the latter it is very short, but in the former it is very
long, and nearly formed by a single jomt. In Eurhimis
Kirby, a New Holland genus of the weevil-tribe, in the
male the last joint, also, is much longer than it is in the
female These examples will give you some idea of the
l^rincipal variations that take place in the antennae of the
sexes, and of the wonderful diversity of forms in this re-
spect to which mere sexuality gives rise amongst insects.

lnt\\eeyes,OY stemmata^ this diversity is less remarkable.
Latreille has described two ants, Formica contractu and
coeca, in the neuter of which he could discover no eyes'*:
in the former, the female, however, had large ones. The
male he appears not to have known, but it probably was
not destitute of these organs ; of the latter he was ac-
quainted only with the workers. The neuter of Mip--
mica rubra, another ant, has no ocelli or stemmata,
although the male and female are provided with them
They are discoverable only ui the former sex of that sin-
gular insect related to the ants, Mutilla europcca. Other
insects differ in the size of the eyes of their sexes. In
the hive-bee, and some EphemercB, the eyes of the drone
or male are much larger than those of the worker and
female, and also meet at the vertex, having their stemmata
below the conflux; whereas in these latter they are
widely distant ^. In Strati/omis, Tabanus, and many other

» Linn. Trans.xii. t. xxii./. 8. <r. <?./. 5 .
• ^ Hist. Nat.des Fourmix, 195—. 270—.
' De Geer ii, 1094,

Ibid. 650. Mon. Ap. Angl. i. t. xl Apis x\. e. 1./. 2. t xij.
/. 3. 5 .

326 STATES OF INSECTS.

two-winged flies, the male eyes meet at some point below
the stemmata, and above the antennae. In the former
they touch more at an angle; for the vertex forming a
narrow isosceles triangle, and for the anterior part of the
face one nearly equilateral : while those of the/ma/^ are
separated by a considerable interval. In Heptatoma
and Hcematopota in that sex, a similar interval obtains;
while in the other, after forming a minute short triangle,
they unite for a considerable space, and then diverging,
form the face. This is also the case in Tabanus; but in
the female, the space that intervenes between the poste-
rior part of the eyes is much narrower than in these two
cognate genera of the horse-flies. In some others of
this order, as Musca Latr., the eyes of the male do not
touch, but approach posteriorly much nearer to each
other than those of the other sex. In a few instances
the sexes vary even in the number of their eyes, as well
as the size. This occurs in some species o( Ephe?nera L.
(E. diptera, &c.), in which the male, besides the com-
mon lateral ones, has two large and striking mterme-
diate eyes, that sit upon vertical pillars or footstalks'.

2 The Trunh The thorax of many coleopterous
males, especially of the Di/nastid^ and Coprid^ amongst
thepetalocerous tribes, exhibits very striking differences
from that of the female. In many Lncam the lateral
ancrle is more prominent. In Anthia it is bilobed poste-
riorly, while in the last-mentioned sex it is entn-e . In
Phancus-carnife. MacLeay {Copris F.) itis elevated into
a plane triangular space, with the vertex of the tnangle

» Platb XXVI. Fig. 39. Dc Gccr-ii. 051. 659.
b Voet Colcupl. i. i. xxxix./. 47, 48. <? . 46. ? .

STATEsS OF INSECTS. S27

jwiiiting to the head; but in the female it is convex, with
an anterior abbreviated transverse ridge ^.

In a large proportion terrific horns, often hollow, like
those of the head lately noticed, arm the thorax of the
male, of which you will usually only discover the rudi-
ments in tlie other sex. In the first place, some are imi-
corns, or armed only with a single thoracic horn, which
frequently, in conjunction with the thorax itself, not a little
resembles a tunnel reversed : of this description are Dj/-
nasles Hercules, Tityus, Gedeon, Enema, &c. ^ In the
three first this horn is porrected, or nearly in the same line
with the body; but in the last, and D. Pan,.\t forms an
angle with it ; and in D. Mgeon it is nearly vertical <=.
In Z). Hercules it is very long; in D. Alcides^ and Tityus
very short; in the two last, and in Oxytclus tricornis
which is similarly armed* it is undivided at the apex ;
but in D. Gedeon, Pan, hilobus, &c. "= it is bifid or bilobed.
It is usually rather slender, but in D. Chorinceus ^ and
bilohiLS, it is veiy stout and wide. In B. claviger it is
hastate at the apex s. In D. /lastatus it is short and
truncated''. Others, again, have two thoracic horns.
In Copris nemestrinus these are discoidal, diverging, and
inclming forwards K In Phanceus Jloriger^ they are late-
ral, triangular, and incline towards each other, with, as
it were, a deep basin between them. In P. spleiididulus
they sink into two longitudinal ridges, most elevated

" Oliv. no. 3. t. \\.f. 46. a. <J . 5 . _
" Ibid, t.i.f. 1. iv. X./. 31. xi./. 102. xii./. 114.
•= Ibid. t. xxvi./. 219. u ibij, t i./ 2.

' Ibid. t. xxiii./ 35. f Ibid. i. W.f. 7.

Mbid./.v,/.40. " lbid,xix./.]75.

' Ibid. Z. xii./. 115.

^ Copris Jiurigcr Kirby mLiim. Tram. xii. 306.

328

STATES OF INSECTS.

posteriorly, with an intervening valley In P. bellicosus
they are posterior, compressed, truncated, and emargi-
nate at the apex, and include a basin In Copris Sabceus
they are merely two acute prominences <=. — T7iree horns
distinguish the thorax of many. In D. Aloeus^ and its
affinities, they are arranged in a triangle, whose vertex
is towards the head. In D. Antceus = these horns are
nearly equal in length, and undivided at the apex. In
Z). Titanus ^ the anterior horn is longer than the rest,
and bifid at the apex ; in D. Atlas and Eiidymion^, both
of which have a horn on the head, it is much shorter.
In others, as in Megasoma Kirby, the vertex of the tri-
angle is towards the anus. In M. TypJion it is longer
than the anterior ones, and bifid at the apex ; in M. la-
nigerum they are equal in length In M. Eleplias and
Actceon " it is merely an elevation of the thorax ; in the
last almost obsolete. In Geotrnpes Typhceus, common
on our heaths, the anterior of this part is armed by three
horizontal horns, the intermediate one being the short-
est Copris lunaris also, another of our own beetles,
has three short posterior thoracic horns, two lateral and
triangular ones, and a transverse intermediate elevation,
with a notch in the middle In Dynastes Neptunus the
horns are porrected, the middle one being very long, and
the lateral ones short In D. Geryon the point of the la-
s' Oliv. no. 3. t. ilf. 18. " Ibid. t. xxii./. 32.
« Ibid. /.ix./. 85.- " Ibid.f.iii./.22.
• Ibid. t. xiii,/. 124. a. ' Ibid. t. v./. 38.
8 Ibid. t. xxviii./. 242. t. xviii./. 169.

Ibid. t. xvi./. 152. * Ibid, t xxvm./. ^4/,

k Ibid.i. XV./. 138. a. t. v./ 33.
' Samouelle's Compencl, t. If. 1.

- Oliv. no. 3. L V./. 36. a. " ^^chon. Synon. i. /• 1.

STATES Of JNSECTS.

329

teral horns is towards the anus, and the base of the in-
termediate one covers the scutellum *. Others have four
of these singular arms : this is the case v^\\h one of our
rarest beetles, Bolbocerus mobilicornis K., which has four
dentiform horns, the intermediate pair being the short-
est, arranged in a transverse line on the anterior part of
the thorax ^. In B. quadridens these are merely teeth.
In PhancBus Faumis it has two lateral, elongated, com-
pressed, truncate, horizontal horns, and two intermediate
teeth. Dynastes Milon has a still greater number of
horns on the thorax of the male, there being two lateral
anterior ones and three posterior ones — the intemiediate
being the longest''; and Copris Antenor Fabricius and
Olivier describe as having a many-toothed thorax; and
from the figure of the latter the male appears to have
seven prominences.

But the males of insects are not only occasionally di-
stinguished by these dorsal arms — in a few instances they
are also furnished with pectoral ones. The illustrious
traveller Humboldt found in South America a species
of weevil [Cryptorhynchus Spicidator Humb.), the breast
of which was armed with a pair of long projecting horns;
and I possess both sexes of four species, three at least
from Brazil, that exhibit in one individual the same cha-
racter. One, concerning the counti-y of which I am un-
certain, recedes somewhat from the type of form of the
rest, and comes very near that of Rynchccnus Strix F. ^
In the individual which I take to be C. Spicidator, the
pectoral horns are very long, curving upwards at the

» Oliv. no. 3. t. xxiv./. 208, ^ Ibid t. x f. 88.

'Il^"'-/87. Ibid XX./. 185.

' Ibid. I- vi./. 42. a. i ibid. n. Sd. Curculio / xxii./ 205

330 STATKS or fNSECTS.

apex, unci nearly in a horizontal position ; while in the
three others they are much shorter, and inclined towards
the horizon. The males of some species of Byiichites, as
B. Bacchus and Populi % are also armed with a pair of
lateral horns or spines, which may be termed pectoral
rather than dorsal.

I shall now advert to the sexual characters that are to
be found in the instruments of motion attached to the
trunk— beginning with those for fight. In the female of
the common glow-worm {Lampyris noctiluca) not the
slightest vestige of elytra or wings is visible, and it re-
sembles a larva rather than a perfect insect; yet its mate
is a true beetle furnished with both. The same circmn-
stance distinguishes the female cockroach {Blatta) and
is more universally prevalent in that genus than in Lam-
pyris, in which a large number of females have both ely-
tra and wings. The males of Bovihyx antiqua and Gono-
stigma, and of many other moths, have wings of the usual
ample dimensions, while those of their females are merely
rudiments. This is the case, also, with some of the Ich-
neumonid^K In the tribes of Ants, Termites, &c. the
neuters or workers are without wings. Amongst the
plant-lice {Aphides) there are individuals of both sexes,
some of which have wings, and others not <=. Amongst
the Coleoptera, the female of Te^iebrio Molitor, the com-
mon meal-worm, has elytra and no wings; while the
male has both <i.— Sometimes these organs vary m size
in the sexes: thus in Aradus Bettdcc F., a kind of biig,
the hemelytra and wings are narrower and shorter m the

a Oliv. no. 81. AUelabits i. ii./ 27. b. 28. ■ „

• e ^Q OO ^- IbKl. 111.

1' De Geer li. t xxxi /. 18—32. i^'"-
•* Lesser L. i. 185.

STATKS OF INSECTS.

831

female than in the male ^ In the genus Blaps F., the
mucro that arms the apex of each elytrum is longer in
the former sex than in the latter. In Ateuclius gihho-
sm F., a dung-beetle, the elytra have a basal gibbosity
near the suture in one sex that does not obtain in the
other. In the Ortlioptera order, the sexes are often to
be known, almost at first sight, by a difference in the
veining and areolets of the wings ; but upon this I en-
larged so fully when I treated of the sounds produced by
insects, that it is not necessary to repeat what I have
said ; which observation also applies to the drums which
distinguish the male Cicadce ^. The wings of some but-
terflies, and of most moths and hawkmoths {Sphinx L.),
are furnished with a singular apparatus for keeping them
steady, and the under-wing from passing over the upper
in flight. This appears to have been first noticed by
Moses Harris, and was afterwards more fully explained
by M. Esprit Giorna ^. From the base of the under-wing
proceeds a strong bristle, received by an annulus or
socket, which springing between the two principal ner-
vures of the upper-wing terminates in the disk of the
wing : in this annulus the bristle moves to and 6*0, and
prevents the displacement of the under-wing. This ap-
pai'atus is perfect only in the males, which alone have
occasion for long flights ; the females, though they have
often several bristles, having no annulus ^.

The other instruments of motion, the legs, also differ in
the sexes. In some instances they are disproportionably
long. This is particularly the case with the anterior pair

" Dc Gcer Hi. 308. ^ See above, Vol. II. 394—.

Linn. Trans, i. 1-15. 135 — .
I6id. t. xiii./. 1. 2. ^ . 3. $ .

332 STATES OF INSECTS.

of some beetles, as Macropus longimanus, Scarabceus longi-
manus L., in whicli they are so long as to make the males
of these individuals rather inconvenient in a cabinet.
Amongst British beetles Clytra longimana and Curcuiio
longimanus Marsh, are also remarkable in this respect.
In some other males the middle pair are the longest; as in
Anthoplwra retusa Latr., a kind of wild-bee \ There are
two known instances of remarkably long pos^erwr legs in
the Capricorn tribe, which I suspect belong to the present
head. One is Sajperda hirtipes Ohv.^ in which thehind-legs
are longer than the whole body, and adorned with a sin-
gular tuft of hairs ; and the other a Clytus, I think, which
Mr. MacLeay purchased from the late Mr. Marsham's
collection, in which the hind-legs are not only very long,
but have tarsi convolute, like some antennae. From ana-
logy I should affirm that these were the characters of
male insects.

To come to the parts of legs. Sometimes the cox(E of
the last mentioned sex are distinguished from those of
the female by being armed by a mucro or spine. Thus
the male of MegacMle Willughhiella, and others of that
tribe, have such a spine on the inner sides of the anterior
coxa<=. The Trochanter also of some differs sexually;
and you will find that the posterior one of the male in
Anthidhm manicatum is of a different shape fi'om what
it is in the female In Sphodnis leucoptlithalmus, one of
the beetles called black dors, in one sex the same tro-

» Mon. Ap. Angl. i. t. xi. Apis **, a. 2. et. /3./.
b Oliv. no. 68. Sapcrda t. If. 8.
« Mon. Ap. Angl. i. t. viii./. 28. c.
1 Ibid. t. ix. Api5*». c.2.f3./.13.

STATES OF INSECTS. 333

chanter terminates in a long mucro or spine % and in the
other it is rounded at tlie apex.

Peculiar characters in their thighs also often mdicate
different sexes. In Prionus damicm-nis there is a short
spine at the apex of the anterior ones in the female that
is not in the male ; while in Macropus longimanus, at their
base externally the male is armed with a mucro, which I
cannot find in the female ''. In Scarahceus longimanus L.
this thigh is furnished with two teeth — The interme-
diate thighs also sometimes differ. In an Onitis fi'om
China, a variety perhaps of O. Sj^hinx, those in the male
are dolabriform, and in the other sex of the ordinary
shape. In Odynerus spinipes they have on their lower
side two sinuses, so as to give them the appearance of
being toothed. The posterior thighs are sometimes in-
crassated in the male, and not in the female. This you
will see in a weevil, not uncommon, Apoderus Betulce,
and also in many species of Cimbex F., a kind of saw-fly ;
and the same circumstance distinguishes the latter sex in
many species of Lygceus F., a kind of bug : I discovered
this from L. cruciger, of which I have both the sexes ; and
from StoU's figure of L. Pharaonis ^. In some of these
the female thighs are enormously large. A remarkable
variation in this respect is observable in the coleopterous
genus (Edemera {Necydalis L.). In CE. Podagrarice these
limbs are incrassated in one sex and not in the other
in G?. ccendea they are so in both sexes; and in ^E. cerajn-

" Clairv. Ent. Helv. ii. t. xii./. B.

OHv. Ins. no. 66. t. iii. iv./. 12. • Ibid. no. 3. iv./. 27.

Punaiics, t. iii./. 20.
* Mr. Marsham has made two species of tiiis from this circum-
stance, viz. Necydalix Podagraria; and sinqilex.

334. STATES or insects.

boides in neither. In Pelecinus Polyceraior F., one of
the Ichneumon tribe, or an insect very near it from Bra-
zil, these thighs in the female are armed with two spmes
underneath, which are not in the male.

The anterior tibia in ScarahcEUS longimanus L. differ
remarkably in the sexes. In the female they are of the
ordinary shape, and serrated externally; but in the male
they are very long, incurved, and without teeth or serra-
tures^ In the males of the genus Onitis F. they are bent
like a bow, and acute at the end ; but in the females they
are formed on the common type ^ In Hispa spinipes F.
they are armed internally with a crooked spine <=. But
the most extraordinary sexual variation of this joint of
the leg may be seen in the male of Crahro cribaritis Y.
and several other species of the same family, in which
these tibise are dilated externally into a concavo-convex
plate, or rather have one fixed to them and part of the
thigh, of an irregular and somewhat angular shape ^
with numerous transparent dots, so as not badly to re-
semble a sieve: whence the trivial name of the species.
Rolander, who first described it, fancied that this plate
was really perforated, and that by means of it the anunal
actually sifted the pollen ; but it is most probably for
sexual purposes. In another species, the plate is orna-
mented with transparent convergmg streaks. In the
bee-tribes {Anthophila Latr.) the posterior tibia of the
working sex is generally bigger than the corresponding
part in their more idle partners : this is particularly con-

a Oliv. n. .3. t. xxvii./. 27- ? . and t. iv./. 27- <? •
"> Ibicl./.vii./.58. ^./.57. ?.
« Ibicl.n.95. HhpatA.fA. Plate XXV1I.Hg.24.
'1 Pi.A ri; XV. Fig. :5.

STATES OF INSECTS.

335

spicuous in the genus Euglossa, in the females of which
this part is triangular, vei'y broad towards the apex, and
fitted for carrying a large mass of pollen paste. The
tibiee of the males of some Lepidoptera are remarkable in
tliis respect. That of Hepiahis Humuli is much more
hairy ; but in H. Hectus it is a dilated mis-shapen mass,
without a tarsus, and with long scales pendent from the
disk ^. Differences of this kind also occur in the calcaria
or spurs that arm the apex of the tibi^ of a large num-
ber of insects. Thus in Acanthopus Klug, a singular
bee, in tlie male the spur of the intermediate leg is dilated
at the apex, and armed with six strong spines, the inner
one larger than tlie rest''.

But the part of the leg in which the sexes most vary
is the tarsus ; and this variation takes place both in the
number of the joints, and their form and circumstances.
The first case has been observed only with regard to cer-
tain species of Cryptophagus Herbst, as C.fumatics, &c.
in which the female is pentamerous, or having^u^ joints
in all the tarsi; and the male hete}-ome?-ous, or having
joints in the two anterior pairs, and only four in the
posterior <=. With respect to the form of the tarsal joints,
the sexes more frequently differ ; and by inspecting this
part, especially in the predaceous and carnivorous Co-
leoptera, you may often, without fiirther examination,
ascertain whether any individual is male or female.
Even in the slender-footed Cicindelid<e, the three first
jomts of the anterior tarsus of the male are more dilated
than the two last, and covered underneath with a brush

» De Geeri. t. vii /. 14, 15.
Coquebert Illust. Icon. I ( vi f. C. Plate XXVII. Fig. 33.
Illig. Mag. iv. 21 4. Gyllenhal. luaecL i'j/rr. i. I G8.

fi36 STATES OF INSECTS.

of stiffish hair; m the female all are equally slender, and
not SO hau-y. In Carahus, Feronia, &c. Latr. the/our first
joints of these tarsi in the males are dilated, and furnished
with a brush or cushion: in the Silphidce, also, the same
circumstance takes place. In Harpalus Latr., and Sil-
•pJia americana, the four anterior ones are similarly fonned
in this respect. But one of the most remarkable sexual
characters, in this tribe of insects, that distinguish the
males, are those orbicular patellae, furnished below with
suckers of various sizes, and formed by the three first
joints of the tarsus, which are to be met with in the Dy-
tiscidcc, &c. ; but as I shall have oocasion to treat of these
more fully in another Letter, I shall only allude to them
now. The second pair of tarsi have in these also the
three first joints dilated and cushioned \ In Hydro-
;philus piceus, another water-beetle, the fifth joint of the
tarsus is dilated externally, so as to form nearly an equi-
lateral triangle ^ Christian, a German writer on the Hy-
menaptera, has described some very singular appendages
which he observed on the first joint of the four posterior
tarsi of Xylocopa latipes F. These Avere battledore-
shaped membranaceous laminae, with a reticulated sur-
face, of a pale colour; which were fixed m pairs by the
intervention of a footstalk to the above joint, on which
they sometimes amounted to more than a hundred: the
use of which, he conjectures, is the collection of poUen ^
I possess two specimens of this bee; one has none of
these appendages, and on the other I can discover them
only in one of the tarsi— from which circumstance I am

a Plate XV. Fig. 9. " Ibid. Fig. 8.

e Christ. Hymempt, 118. iv./. ^-

STATES OF INSECTS. <^37

led to conjecture that, like the supposed Clavarice that
were imagined to grow on some humble-bees, but wliich

are now ascertained to be the anthers of flowers these

also belong to the kingdom of Flora, and are spoils which
the bee in question has filched from the blossom of some
plant. The individuals that have been thus circum-
stanced are males ; whether the female is guilty of simi-
lar spoliations is not known. In my specimen there are
no traces of them. In many bees, the first joint of the
posterior tarsi is much larger in the females and workers
than in the males; but in the hive-bee this joint is larg-
est in the latter ^ In Ba'is clavipes and Empis nigra^
two flies, the joint in question is large and thick in the
male, but slender in the female. The penultimate tarsal
joint in the posterior legs is dilated internally, and termi-
nates in a mucro in one sex of AnoplognatJms Bytiscoi-
des of Mr. W. MacLeay In some insects the anterior
tarsus of the males has been supposed to be altogether
wanting : I allude to the petalocerous genus Onitis F. ;
but I have a specunen of Onitis Apelles of this sex, or a
species nearly related to it, in which one of these tarsi
is to be found which, though very slender, consists of
five joints, and is armed with a double claw : from which
circumstance it may, I think, be concluded, that although,
as in PhancEiis, these tarsi are very minute, they are not
wanting, mat renders this more probable is, a circum-
stance which every collector of insects, who has many
specimens of Mr. W. MacLeay's Scarabceidce in his ca<
binet, must have noticed : namely, that in all, except Co-

» Mon. Ap. Angl. i. /. xi. Apk **. e. \. S ./. 8. a. and t. xii.
e. 1. neut./. 19. c.

" Hor, Enlomolog. 144. ' Plate XXVII. Fig. 45. a.

VOL. III. V

■gggss —

333 STATES OF INSECTS.

pris and Onthophagus, the anterior tarsi are usually broken
off. Out of seventeen individuals of ScarahcEus MacLeay
in my own, not a single one has a relic of an anterior tar-
sus ; and scarcely one in a much greater number of Pha-
nm. The tarsus in question in the nobler sex m Crahro,
at least in C. cribrarius and its affinities, is also very short,
especially the three intermediate joints ; but at the same
time very broad and flat. In the species just named, the
external claw forms a kind of hook; and in the rest it is
considerably longer than the other \ The cla^s, mdeed,
occasionally vary in the sexes in other Hymenoptcra :
thus in Mdecta Latr., a kind of bee, in the female they
are intire, but in the male they are furnished with an m-
ternal submembranaceous tooth or process \ In Cceh-
oxys conica and others, those of the latter sex are bifid at
the apex, but those of the former acute ^ In Megaclnle
the male claw is as in the instance just mentioned, while
the female hits a lateral tooth ^; and a similar character
distinguishes the sexes in the hive-bee ^

3 The abdomen. This part affords many external
sexual characters, whether we consider its general shape;
the number of segments that compose it; its base, mid-
dle, or extremity.

In general shape it often differs in the sexes. Thus,
the abdomen of female Tipulc, is lanceolate; that of the
male cylindrical, and thickest at the extremity . in

a DeGeerii.i.xxviii./.2. . m j 11 Q

b Moil. Ap. Angl. i. t. V. Apis **. a./. 10. 5 . H- 'i ■
c J6i^i.f.vii.Apis**.c.l.«. 17. ?. 18- <?•

d ^.viii./. 30. ^.31. ?• . •. *« p i fem /•. 9.

e md. t. xi. Apis **. e. 1. mas./. 9. t. xu Apis **• e^l- fem. /
and ncut./. 2^. r De Geer vi. xvm./. 12. 13.

STATES OF INSECTS.

339

Molorchus F. it is convex above in the former, and flat
in the latter, — the female of this beetle not unaptly repre-
senting some female Ichneumons in this respect, and the
male their males ^ In Andrena it is oblong in the one,
and lanceolate in the other. In the hive-bee the drones
have a thick, obtuse, and rather long abdomen ; in the
females it is long, and nearly represents an inverted cone;
and in the workers a three-sided figure, or prism.

The number of segments, also, is generally different in
the two sexes — the male having one more than the female;
but in Dytiscus marginalise Sec. the reverse of this takes
place : the female, if you reckon the bipartite half-con-
cealed anal segment as one, having seven ventral seg-
ments, and the male only six. She has also eight dorsal,
and the male seven. — In the ant tribes {Formica L.), the
little vertical scale, at the base of the abdomen in one
description of them, or the double knot in another, is
less in the male than in the female. In a very singular
male insect belonging to the Vespida, and related to Sy-
nagris, (which I purchased from the late Mr.Drury's ca-
binet,) the second ventral segment sends forth from its
disk two remarkable parallel very acute and rather long
spines. The same sex of Chclostoma maxillosa has like-
wise on the same segment a concave elevation, opposite
to which on the fifth is a cavity which receives it, when
the animal rolls itself up to take its repose ^. In another
species, C. Camjpamdarum, the segment in question has
only a tubercle

On the second segment of the abdomen of some spe-
" De Geer v. 151—.

" Mon. Ap. A,igl. 1 177. t. ix. Apis c. 2. y.f. 1 1 . ^d.
' Idid.f. 13.«. ^ J '

z 2

340 STATES OF INSECTS.

cimens, probably males, of the remarkable African ge-
nus Pneumora before alluded to % there are thirteen lit-
tle elevated ridges, platred rather obliquely in an oblique
series; and gradually, though slightly, diminishing in
size towards the belly: on their upper side they are flat,
forming nearly a horizontal ledge, but on the lower they
slope to the abdomen. The posterior thigh in its natu-
ral position covers the three first of them, and, if moved
downwards, would strike them alP. I conjecture, there-
fore, that these are the animal's instruments of sound,
imitating the harp or violin rather than the drum; and
that the thigh acts the part of the hand or bow. The
abdomen of these insects being blown out like a bladder,
and almost empty % must emit a considerable sound when
the thigh of the animal passes briskly over these ridges;
and their different length would produce a modulation
in the sound. When struck with a pin, they emit a gra-
ting noise.

In Staphylinus splendens, the pemdtimate ventral seg-
ment is very deeply cleft, and the antepenultmiate emar-
ginate in one sex, and intire in the other. In S. laimna-
tus, an allied species, the penultimate segment is clefi,
less deeply, however; but the antepenultimate is very
short and intire; while the fourth is extremely long, and
rounded at the margin, appearing as if it was only an
elevated part of the last-mentioned segment; for which
it was mistaken by Gravenhorst while it is of the usual
form in the other sex.

^ See above, Vol. II. 395.
• b Plate XXIX. Fig. 13- Stoll Spectres, &c. i. xxv./.
<^ Span-man. Voyage, i. 312—.
Co/eopf . Micropt. 16,

STATES OF INSECTS.

341

The extremity of the abdomen or its anal segments
and organs furnish a variety of sexual characters. Some-
times the last dorsal segment is emarginate in the male,
and not in the female ; as in Megachile lig7iiseca, one of
the leaf-cutter bees, Ci7Hex hcemotr/ioidalis, &c. * At
other times little lateral teeth are added to this notch, as
in another of the same tribe, M. Willughbiella ^. Agam,
in other males, both the ventral and dorsal anal segment
are armed each with a pair of teeth or mucros, as in
Chelostoma maxillosa". In Anthidium manicatum, an-
other bee, the anus terminates in five spines In Cceli-
oxys conica of the same tribe, in which this part in the
female is very acute, that of the male is armed with six
points In that singular Neuropterous genus Panorpa,
while the abdomen of the female is of the ordmary form,
with a pair of biarticulate palpiform organs attached to the
last retractile joint, or ovipositor, that of the male tenni-
nates in a jointed tail, not unlike a scorpion's, at the end
of which is an mcrassated joint armed with a forceps ^ In
the common earwig {Forficnla auricularia) the two sexes
differ considerably in their anal forceps : in one it is armed
with internal teeth at the base, and suddenly dilated, above
which dilatation it is bent like a bow : in the other it is
smaller, without teeth, gi-ows gradually narrower, is
very minutely crenulate from the base to the end, and is
straight, except at the very summit, where it curves m-
wards. Misled by these and similar differences, Mr. Mar-

" Afw- Ajj. Atigl. i. t. viii./. 25. De Geer iii. 255. /. xiv./. 8.

•> Moil. Aj}. A7igl. i. t. viii./. 24. « I6id. t. ix. Apis xx. c. 2. y.f. 12.

Ibid. Apis •». c. 2. /3./. 11.
• /^jrf. t. vii.Apis**. c. 1. «./. 11, 12. ? . 1.3, 14. <?.
' Plate XV. Fig. 12. De Gccr ii. I. xxiv./. 9, 10. ? . t. xxv.
/. 2, 3. .

34,2 STATES OF INSECTS.

sham has considered them (the sexes both of F. auricu-
laria and F. minor) as distinct species.

The tail of some species of the genus Ephemera is fur-
nished with three long, jointed, hairy bristles. We learn
from Reaumur with respect to one, that though m the
female these are all equal in length, yet in the male there
is only a rudiment of the third. On the belly near the
anus these males have four fleshy appendages, the poste-
rior ones setaceous and long, and the anterior pair hli-
form and shorter. They are supposed to represent the
anal forceps of other insects ^ In Ephemera mlgata,
described by De Geer, both sexes have three brisdes,
but those of the male are the longest; and he describes
the forceps as consisting of only a pair of jointed pieces,
forming a bow not unlike the forceps of an earwig .

V All the differences I have hitherto noticed between
the sexes of insects occur in their bodily structure; but
there are others of a somewhat higher description ob-
servable in their character. You may smile at the idea
of character in beings so minute; but if you recollect what
I formerly related to you when treating upon the socie-
ties of insects, you will allow that something of this kmcl
does take place amongst them. In general the males are
more fitted for locomotion and more locomotive; and
the females, on the contrary, are necessarily more sta-
tionary. And this for an obvious reason :-the law is
that the male shall seek the female, and therefore he is
peculiarly gifted for this purpose, both in his organs ot
■ Lation'l motion: while his partner in many cas^
' has very simple antenna, he has very complex ones; and

» Reaum.vi.494./.xliv./3-ll. '> De Gecr iU. xvii./ 5-7-

STATES OF INSECTS.

343

while she has either no wings or only rudiments of them,
he is amply provided with them. Again : amongst the
insects that suck the blood of man or beast, such as the
gnat {Culex) or horse-flies {TabanidcE\ it is the female
alone that is bloodthirsty, the males contenting them-
selves with the nectar of flowers But the difference of
character in the sexes is most conspicuous, at least it has
been more noticed, in those that live in societies, and is
quite the reverse of what takes place in the human spe-
cies. While the females and workers (which are now
generally considered as sterile females, in which the ova-
ries are not developed) are laborious and active, diligent
and skilful, wise and prudent, courageous and warlike; —
the males, on the contrary, take no part in promoting the
common weal, except merely a sexual one. Though till
a certain period they are supported at the expense of the
community, they take no part in its labours, either in
collecting and forming the public stores, or in feeding
and attending the young. They are idle, cowardly, and
inactive ; have neither art nor skill of any kind, and
are unprovided with the usual offensive weapons of theii
species. These observations in their full force apply par-
ticularly to the hive-bee, and partially to the other social
insects; amongst which, if you consult my former com-
munications, there are some exceptions to this slothful
character in the males

II. Age. There is less diversity in the duration' of the
lives of insects in their perfect than in then- larva or pupa

* N. Diet. d'Hist. Nat. xxxii. 44,'5.
" See above, Vol. II. 110, 118.

314 STATES OF INSECTS.

State. Some, like several species o^ Ephemera:, live only
a few hours ; some never even see the sun ' : others, as
flies, moths, and butterflies, and indeed the majority of
insects, a few days or weeks ; and a comparatively small
number, such as some of the larger Coleoptera, Or tho-
ptera, &c., six, nuie, twelve, or fifteen months— a period
beyond which the life of perfect insects rarely extends.
Some, however, certainly enjoy a longer existence in the
perfect state. Mr. Baker kept one of the darkling beedes
( Blaps Mortisaga) alive under a glass upwards of three
years. The rose-beetle {Cetonia aurata\ Rosel informs
us he fed with fruit and moist white bread for as long a
period''. Esper kept our most common water-beetle
{Dytiscus marginalis) in water in a large glass vessel,
feeding it with meat, for three years and a half With
regard to the Arachnida, from the very slow growth of
Scorpio europaus, Rosel suspects that it must Uve two
or three years ; and Audebert is stated to have kept a
spider for several In this respect insects follow a law
very different from that which obtains amongst verte-
brate animals. In these the duration of their life is m
proportion to the term of their growth : those which at-
tain to maturity the latest, in almost every case living t,he
longest. In insects, on the contrary, we often meet with
tlie very reverse of this rule. Thus the larva of the great

a Vol. 1. 283. " II. i. 6.

c Clairville Ent. Helvct. ii. 214—. I have seen it asserted m some
popular work on Natural History, (the title of which I do not recol-
lect ^ that Mantis religiosa has been known to live ten years ; and a
flea v^hen fed and taken care of, six. But this is so contrary to expe-
rience in other cases, that the statement seems quite mcredible.
Rdsel III. 379. Did. d'Hist. Nal. ii. 285.

STATES OF INSECTS.

34.5

goat-moth {Cossiis ligniperda) is three years, that of the
cabbage-butterfly (Pieris Brassicce) not three months, in
attaining matm'ity; yet the perfect insects live equally
long. Melolontha vulgaris, which in its first state lives
four years, as a beetle lives only eight or ten days
And some EphemertE, whose larvae have been two years
in acquirmg their full size, live only an hour ; while the
flesh-fly, whose larva has attained to maturity in three or
four days, will exist several weeks.

There is yet another anomaly in the duration of the
life of perfect insects. This is not, as in larger animals,
a fixed period liable to be shortened only by accident or
disease, and incapable of being prolonged ; but an inde-
terminate one, whose duration is dependent on the ear-
lier or later fulfilment of a particular animal function —
that of propagation. The general law is, that a few days,
or at most weeks, after the union of the sexes, both pe-
rish, the female having first deposited her eggs. If,
therefore, this union takes place immediately after the
disclosure of tlie insect from the pupa, their existence in
tlie perfect state will not exceed a few days or >voeeJcs, or
in some cases Jiours, as in that of the Ephemera, and hke-
wise of the PhalcencB Attaci L. &c., which fall down dead
immediately after oviposition ^ But if by any means it
be put off or prevented, their life may be protracted to
three or four tunes that period. Gleditsch asserts, that
by keeping apart the sexes of a grasshopper, their lives
were prolonged to eight or nme weeks, instead of two or
three, their ordinary length; and mider similar circum-
stances Ephema-ce, which usually perish in a day, have

' D^nicril Trallc Elhnenl. ii. 87. n. 683. •< Dc Goer ii. 288.

346 STATES Ob" INSECTS.

been kept alive seven or eight. It is in consequence of
this very curious fact, which has not received from phy-
siologists the attention that it merits, that many butter-
flies and other insects, which, when excluded from the
pupa in summer, perish in less than a month, live
through the winter, if excluded late in the autumn, and
the union of the sexes does not ensue. It is probable
that the great age to which Baker's Blaps, Rosel's Ceto-
nia, and Esper's Dytisms attained, was owing to their
being virgins when taken, and subsequently kept from
any texual intercourse. A parallel case happens in the
vegetable kingdom :— if annual plants are kept from seed-
ing, they wUl become biennial; as, likewise, if they are
sown too late in the year to produce seeds.

In the case, however, of the earlier or later exclusion
of the imago, another agent has probably some influ-
ence. Buffon found that, other circumstances being alike,
the sUkworm-moths placed in a northern, lived longer
than those exposed to a southern aspect: whence it ap-
pears that the stimulus of heat shortens the lives of m-
sects, and consequently that cold tends to lengthen

them. r 1, f

It must be observed too, that as the death of the fe-
male insect does not take place until all the eggs are ex-
cluded, the term of her life, though usually short m the
majority of species, which lay their whole number at
once, is proportionably long in those which, like the
queen-bee, have a longer period assigned them for this
important office. Huber affirms, that he had certam
proofs that she was engaged for two years in laying eggs,
all impregnated by a single sexual union- and m the

» Iluber i. lOG.

STATE S O F I N S E CTS.

347

females of most insects that live in society, several months
are required to mature the last eggs that are in the
ovary. There is one tribe of insects, however, the fe-
males of which are affirmed to survive this operation :
I mean DortJiesia Bosc ; after which they even moult,
though not so often as before

I formerly related to you the singular fact, that the
drones in a beehive at a certain period are without mercy
slaughtered by the workers A fact the reverse of this
is recorded by Morier with respect to the locusts : he
affirms that the female, when she has done laying her
eggs, is surrounded and killed by the males. He says
that he never himself witnessed this extraordinary cu-
cumstance ; but that he heard it from such authority that
he gave full credit to it <=. It is a fact, however, that
seems to require further evidence to entitle it to such cre-
dit. These are instances in which, by a law of nature,
the life of these insects is shortened by violence. It does
not appear to have been ascertained how long those
drones live that, under particular circumstances, as stated
in a former letter are exempted from the usual slaugh-
ter.

I am, &c.

» N. Diet. (VHisf. Nat. ix. 553. b Vol. II. 173—.

<^ Morier's Second Journey throiigh Persia, 100
<> Vol. II. 175.

LETTER XXXIII

EXTERNAL ANATOMY OF INSECTS.

TERMS, AND THEIR DEFINITION.

Having shown you our little animals in every state,
and traced their progress from the egg to the perfect
insect, I must next give you some account of their struc-
ture and anatomi/. And under this head I shaU intro-
duce you to a microcosm of wonders, m which the hand
of an Almighty workman is smgularly conspicuous.
One would at first think that the giant bulk of the ele-
phant, rhmoceros, or hippopotamus, must include a ma-
chine far more complicated, a skeleton more multifarious
in its composition -covered by muscles infinitely more
numerous-instinct with a nervous system infinitely more
ramified— with a greater variety of organs and vascular
systems in play, than an animal that would scarcely coun-
terpoise a ten-milhonth portion of it. Yet the reverse of
this is the fiict; for the Creator, the more to Hlustrate
his wisdom, power, and skill, has decreed that the mi-
nute animals whose history we are recordnig, shall be
much more complex in all the above respects than these
mighty monarchs of the forest and the flood. Of this
in the present and subsequent letters you will find re-

EXTERNAL ANATOMY OF INSECTS.

349

peated and scarcely credible instances, which in every
rightly constituted mind are calculated to excite, in an
extraordinary degree, those sensations of reverence and
love for the Invisible Author of these wonders, and
that faith and trust in his Power and Providence, which
an attentive survey of the works of Creation has a natu-
ral tendency to produce. And you will not only be
struck by this circumstance, but equally by the infinite
variations in the structure that will present themselves to
your notice ; and that not sudden and per saltus, but by
approaches made in the most gradual manner from one
form to another. And all along, where the uses of any
particular organ or part have been ascertained, if you
consider its structure with due attention, you will find in
it the nicest adaptation of means to an end : a circum-
stance this, which proves most triumphantly, that the
Power who immediately gave being to all the animal
forms, was neither a blind unconscious power, resulting
from a certain order of things, as some philosophists love
to speak*; nor a formative appetency in the animals
themselves, produced by their wants, habits, and local
circumstances, and giving birth, in the lapse of ages, to
all the animal forms that now people our globe ^; but a
Power altogether distinct from and above nature, and its
Almighty Author <=.

* Lamarck Hist. Nat. des Anim. sans Vertcbr. i. 311, 214,
" md. 162. Compare the Systcme des Anim. sans Vertcbr. of the
same author, p. 12—.

The doctrine of Epicurus— that the Deity concerns not himself
with the affairs of the world or its inhabitants, which, as Cicero has
judiciously observed {Be Nat. Deor. 1. 1. ad calcem), while it ac
knowledges a God in %uords, denies him in reality; has furnished
the original stock upon which most of these bitter fruits of modern

350 EXTERNAL ANATOMY OF INSECTS.

I trust that what I have here advanced will excite your
attention to the subject I am now to enter upon; and I
flatter myself, that although at first sight it may promise
nothing more than a dry and tedious detad of parts and
organs^ you will find it not without its peculiar interest

and attraction.

This department of the science— the Anatomy of In-
sects—may still be regarded as m its infancy ; andconsi-

infidelity are grafted. Nature, in the eyes of a large proportion of the
enemies of Revelation, occupies the place and does the work of its
Great Author. Thus Hume, when he writes agamst miracles, ap-
pears to think that the Deity has delegated some or all of his powers
to nature, and will not interfere with that trust. Essays, u. 7o--.
And to name no more, Lamarck, treading in some measure in the
steps of Robinet (who supposes that all the links of the ammal king-
dom, in which nature gradually ascends from low to high, were ex-
neriments in her progress towards her great and ultimate aim-the
fo radon of man!^Bai-clay On Orga^nzation, &c. 263), thus states his
opinion: « La nature, danstoutes ses operations, ne pouvant pro-
ceCi que graduellement, n'a pu produire tons les anmiaux a-la-fois

II n'a d'abord form6 que les plus simples; et passant de ceiix^i
Ssaues aux plus composes, elle a etabli successivement en eux dif-
i r sytt Jes d'orgfnes particuliers, les a multiplies en a -gi.-
de plus en plus I'energie, et, les cumulant dans les P^- P^^f ^^^^t
a fait exister tons les animaux connus avec I'-g--^-^ ^^^.^
cultes que nous leur observons." {Anm. sans Vcrtebr. i. 123.) 1 hus
denig to the Creator the glory of forming those works of ere.
S the animal and vegetable kingdom (for he assigns to both the
s^eorU. Ibid- 83), in which his glorious attributes are most con-

pkuousfy manifested; and ascribing them to nature, or aca^
ZZofLgs, as he defines it (214)-a blind power, that operates
ordei oj b . however, to be the product of

n,n„e,- Epicurus, Be UM. dum »» ..«<- "''Yff''"^■J■^Z^^-
he i«-ribes all to «»(»>■<•; yet as the m«cd,alc cause of all

EXTERNAL ANATOMY OF INSECTS.

351

dering the almost insuperable difficulties which, from the
muiuteness of the objects, oppose themselves to the skill
and instruments of the entomological anatomist, we can
scarcely hope that it will ever attain to that certainty and
perfection to which, as far as the larger animals are con-
cerned, anatomy has arrived. Yet infinitely more has
been accomplished than might have been expected, and
new accessions of light are daily thrown upon it. When

raal forms, he refers to the local circumstances, wants, and habits of
individual animals themselves ; tliese he regards as the modifiers of
their organization and structure (102). To show the absurd nonplus
to which this his favourite theory has reduced him, it will only be ne-
cessary to mention the individual instances which in different works
he adduces to exemplify it. In his St/stemc, he supposes that the
web-footed birds {Ameres) acquired their natatory feet by frequently
separating their toes as far as possible from each other in their efforts
to swim. Thus the skin that unites these toes at their base con-
tracted a habit of stretching itself; and thus in time the web-foot of
the duck and the goose were produced. The waders {GrallcB),
which, in order to procure their food, must stand in the water, but
do not love to swim, from their constant efforts to keep their bodies
from submersion, were in the habit of always stretching theii- legs
with this view, till they grew long enough to save them the trou-
ble !! ! (13—). How the poor birds escaped drowning before they
had got theii- web feet and long legs, the author does not inform us.
In another work, which I have not now by me, I recollect he attri-
butes the long neck of the camelopard to its efforts to reach the
boughs of the mimosa, which, after the lapse of a few thousand years,
it at length accomplished ! ! ! In his last work, he selects as an ex-
ample one of the Mo/luscce, which, as it moved along, felt an incli-
nation to explore by means of touch the bodies in its path : for this
purpose it caused the nervous and other fluids to move in masses
successively to certain points of its head, and thus in process of
time it acquired its horns or tentacula ! ! Anim. sans Vertebr. i. 188.
It is grievous that this eminent zoologist, who in other respects
stands at the head of his science, should patronize notions so con-
fessedly absurd and childish.

352 EXTERNAL ANATOMY OF INSECTS.

we consider what has been done by Malpighi, Leeuwen-
hoeck, and especially Swammerdam, we admire the pa-
tience, assiduity, and love of science, that enabled them, in
spite of what seemed insurmountable obstacles, to ascer-
tain, the first with respect to the silk-worm, and the latter
in numerous instances, the internal organization of these
minute creatures, as well as their external structure.
Reaumur, and his disciple De Geer, extending their re-
searches, have also contributed copiously to our know-
ledge in this branch of our science.

But in this field no one has laboured so indefatigably
and with so much success as the celebrated Lyonnet ; and
though his attention was confined to one object— the ca-
terpillar of the goat-moth {Cossus ligniperda F.),— every
one who studies his immortal work must admire the
patient and skilful hand, the lyncean eye, and keen in-
tellect, that discovered, denuded, and traced every organ,
muscle, and fibre of that animal. Much is it to be re-
gretted that his proposed works on the pupa and imago
of the same insect, which, he informs us, were far ad-
vanced% were never finished and given to the world.
Our regret, however, is in some degree diminished by
the elaborate work of M. Herold on the butterfly of the
cabbage {Pieris Brassier), before eulogized''; m which
he has done much to supply this desideratum.

In more modern times, besides Herold, MM. Lati'eille,
lUiger, Marcelle de Serres, Savigny, Ramdohr, Trevi-

. Lyonnet Traite, &c. Pref. xxii. Want of ^ue .nconragem^n^
it is to be feared, caused the abortion of these vahiable treatises.
The MSs!are, Ibelieve, still in existence. It would probably an-
swer now to publish them.

^ See above, p. 52—.

EXTERNAL ANATOMY OF INSECTS. 353

ranusj Sprengel, Aucloin, Chabrier, and, above all, M.
Cuvier in his celebrated Lectures on Comparative Ana-
tomy, have considerably extended the boundaries of our
knowledge in this department : and much of what I have
to say to you in my letters on this subject, will be derived
from these respectable sources. In the exterior anatomy
of insects, I flatter myself that I shall be enabled to make
some material additions to the discoveries of my prede-
cessors ; though few have occurred to me with respect to
their internal organization.

In treating of the anatomy of the vertebrate animals,
it is usual, I believe, to consider, first, the skeleton and
its integuments, whether of skin or muscle, and their
accessories; and afterwards the organs of the different
vital functions and of the senses. But in considering
the anatomy of Insects, the difference before stated % ob-
servable between them and the sub-kingdom just men-
tioned, as to their structure, renders it advisable to divide
this subject into two parts— the first treating of their
extei-nal anatomy, and the second of their internal.—
I shall begin by drawing up for you a Table of the No-
menclature of the parts of their external crust; its ap-
pendages and processes ^ external or internal, accompa-
nied by definitions of them; and followed by such obser-
vations respecting them as the subject may seem to re-
quire for its more full elucidation.

Anatomists have divided the human skeleton into three

* See above, p. 43 — .
There are certain processes which are a continuation of the in-
ternal surface of the crust ,• and serve, as well as the rest of it, for
points of attachment to the muscles : these, though completely in-
ternal, must be considered as parts of the external skeleton.

VOL. in. 2 A

354 EXTERNAL ANATOMY OP INSECTS,

greater sections— the Head, llie T rimk, and the Limbs.
That of hisects, hkewise, is resolvable into ifiree primary
sections, but without including the limbs (wliich, as be-
ing appendages, and therefore secondaiy, had best be
considered mider the section of which they form a part),
for the abdomen in insects, as well as the rest of the body,
being covered with a crust, and forming a distinct part,
may be properly regarded as o. primary section. And in
fact these three parts may be received as primary under
another view— the head, as containing the principal or-
gans sensation ; the trunk, as containing those of mo-
tion ; and the abdovien, as containing those oi generation \
Under each of these primary sections, I shall consider its
respective organs, members, and parts.

You are not to expect to find every part included in
the following Table in every insect; since it has been my
aim to introduce into it, the most remarkable of those
that are peculiar to particular tribes, genera, &c. With
respect to these, I shall generally refer you to the indivi-
duals in which they may be found.

DEFINITIONS.
Corpus (the Body). The whole crust of the insect;
consisting of the Exodenna or external covering, and
the Esoderma or internal cuticle that lines it^. It is
divided into three primary parts, or sections— Cap//,
Truncus, Abdomeii.

» See above, p. 28 — . , • . ^ n.,

» The crust which covers the body of insects is hned internally

with a kind of fibrous cuticle. Query, Whether in any degree ana^

logous to the Periosteum of Vei'tebrate animals ?

EXTERNAL ANATOMY OF INSECTS.

355

I. CAPUT (The Head).
The Head is the anterior section of the body ; con-
sisting of a kind of boK without suture or segment, which
receives the oi'gans of sensation and manducation. It
includes the Os, Facies^ Subjacies, and Collum.

i. Os (the Mouth). That part of the head which re-
ceives and prepares the food for passing into the
stomach. It inckides the Trophi *.

1. Trophi (the Trophi). The different instruments or
organs contained in the mouth, or closing it, and
employed in manducation or deglutition. They in-
clude the Lahrimiy Labium, Mandikdce, Maxilla,
Lingua, and Phat-ynx.

A Labrqm (the Ujjper-lip). A usually moveable or-
gan ; which, terminating the face anteriorly, covers
the mouth fi-om above, and is situate between the
Mandibular. It includes the Appendinda.

a Appendicula (the Appendicle). A small piece some-
times appended to the upper-lip <=. Ex. Halictus ?
Walck. {Melitta **. b. K.)

B Labium (the Uudei-lip). A moveable organ, often
biarticulate, which terminating the surface ante-
riorly, covers the mouth from beneath, and is situ-
ate between the Maxilla'^. It includes the Mcn-
tum, and Palpi Labiales.

a Mentum (the Chin). The lower joint of the Labium,

» We employ this term instead of Instrumenta Cibaria F., to avoid
circumlocution.

' Pf-ATEs VI. VII. &c. a', and XXVI. Fig. 30-33.
Ibid. Fig. 30. Mon. Ap. Angl. i. 139. Melitta *«. h. t. ii./. 4, 5.
Pr-ATEs VI. VII. &c. and XXVI. Fig. 23—29. b'.

2x2

356 EXTERNAL ANATOMY OF INSECTS.

where it is jointed ; in other cases its base. It is
usually seated between the base of the Maxil-

b hABiAi.F.s {the Labial Feelers). Two jointed

sensiferous organs, the use of which is not clearly
ascertained, which emerge, one on each side, from
the Labium, mostly near its summit"^.
C Mandibul^ (the Upper-jaws). Two transverse late-
ral organs, in most insects used for manducation ;
generally corneous, moving horizontally, and clos-
ing the mouth above, under the Labium They
include the Prostheca, Denies, and Mola.
a Prostheca (the Prostheca). A subcartilaginous pro-
cess attached to the inner side, near the base, of the
MandibulcB of some Staphylinidcs " . Ex. Ocypus
similis K., Creophilus maxillosus K., &c.
b Dentes (the Teeth). The terminating points of the
Mandibular. They include the Incisores, Laniarii,

and Molares ^.
A iNCisoREs (the Cutting-teeth). Teeth somewhat
wedge-shaped, externally convex and internally

•■' Plates VI. and VII. a", and XXVL Fig. 34, 35.
The part in this work regarded as the menhm, does not m all
cases accord with what MM. Latreille, Savigj^y. &c. have regarded
as entitled to that denomination. Thus m Hymenopiera, their
Mentum is what we term the Labiun,, while our Mcntuv^ is the
small piece upon which that part sits (Pi-ate VII. Fig^ 3 a > ins
is called the Fulcrum in Man. Ap. Angl. (See i. Explan. of he
Plates.) Our Mentum may generally be known by its situation be-
tween the hinges and base of the AlaxiUa:.

b Plates VI.. VII., and XXVI. b". Ibid.

Plate XIII. Fig. 7. c". . ,

c Marcel de Serres Comparaism des Organes de la MasUcahon des

Orthoptercs. 7- Ann. du Mas. H.

EXTERNAL ANATOiMY OF INSECTS.

357

concave''. Ex. Gryllotalpa Latr., Grijllus Latr.
{Acheta F.), &c. &c.

B Laniarii (the Canine-teeth). Yery sharp and usu-
ally long conical teeth ^. Ex. Forjicula L., Man-
tis L., Libellula L.

C MoLAREs (the Grinding-teeth). Teeth that terminate
in a broad uneven surface, fit for grinding the food'=.
Ex. the herbivorous Orthoptera.

c MoLA (the Mola). A broad, flat, subrotund space,
transversely grooved or furrowed, observable on the
inner side of some mandibles that have no grind-
ing-teeth at their apex Ex. Euchlora MacLeay,
AnoplognatJms Leach, Larva of Lucanus

D MAXiLLiE (the Under-jaws). Two organs moving
subhorizontally, fixed on each side at the base of
the Labium, and often parallel with it — which in
masticating insects seem primarily designed to hold
the food''. They include the Cardo, Stipes, Lohi,
and Palpi maxillares.

a Cardo (the Hinge). A small, transverse, usually
triangular, corneous piece, upon which the Maxilla
commonly sits s.

b Stipes (the S'tett). Tlie corneous base of the iliiz^-

illa, below the Palpus
c LoBi (the Lobes). The parts of the Maxilla above

the Palpus They include the Lobus superior, the

Lobus inferior, and the Ungues,

» Plate VI. Fig. 6. c', a'", and XIII. Fig. 5, a'".

>• Plate VI. Fig. 12. b'". and XIII. Fig. .5. b ".

<= Plate XXVI. Fig. 16. c'". " Ibid. Fig. 20. d'".

« Cuv. Anal. Comp. iii. .322—.

' Plates VI. VII. d'. and XXVI. Fig. 9—15.

s Ibid. e". " Ibid. { ■. •• Ibid. andXXVJ. Fig. 13-15, •

358 EXTERNAL ANATOMY OF INSECTS.

A LoBUS Superior (the Upper-lube). The outer lobe
of the Maxilla, incumbent on the inner one. In
the Predaceous Beetles this lobe is biarticulate and
palpiform''; and in StapJiijlmus olens^ &c. it also
consists of two joints ^ It is called the Galea by
Fabricius, in Orthojxtcra, &c. =

B LoBUs Inferior (the Lower-lobe). The inner lobe
of the Maxilla, covered by the outer one<^.

C Ungues (the Claws). One or more corneous sharp
claws which arm the lobes of the Maxilla In the
Predaceous Beetles there is only one terminating
the lower lobe, with which, in Cicindela, it articu-
lates ; in the Orllioptera and Libelhdina there are
several.

d Palpi Maxillares (the Maxillary Feelers). Two
jointed sensiferous organs, the use of which is not
clearly ascertained, emerging from an exterior la-
teral sinus of the Maxilla ^

E Lingua (the Tongue). The organ situated within
the Labium or emerging from it, by which insects
in many cases collect their food and pass it down
to the Pharynx, situated at its roots above. It va-
ries considerably in different orders and tribes. In
the Orthoptera, Libellulina, &c. it is linguiform,
and quite distinct from the Labium it appears
also distinct in the lamellicorn beetles, Slc."^ In many

Plate VI. Fig. 3. d ". >■ Plate XXVI. Fig. 11. d'".

« Plate VI. Fig. G, 12. d'".
d Ibid. Fig. 3, 6, 12. and XXVI. Fig. 9, 10. e'".
« Ibid. VI. Fig. .% 12. f ".

f Plates VI. VII. h". XIII. Fig. 1—4, 8. h . and XXVI.
Fig. 1-8. ' P^-vri^ VI. Fig. 6, 12. e'.

" Plate XXVI. Fig. 36,29. c.

EXTERNAL ANATOMY OF INSECTS.

359

Hymenoptera it emerges from the Labium-^ and is
fitted to collect liquids and pass them downwards
In Formica it appears to be retractile In a con-
siderable proportion of insects it seems connate
with the Labium^ and forming its inner surface?
According to circumstances it might perhaps be
denominated Lingua or Ligiila. It includes the Pa-
raglossa.

a Paragloss^ (the Paraglossa). Lateral and often
membranous processes observable on each side of
the tongue in some Hymenoptera, &c. <=

F Pharynx (the Phaiynx). The opening into the gul-
letIt includes the Epipharynx and Hypopha-
rynx.

a Epipharynx (the Epipharynx). A small valve under
the Labrum, that in many Hymenoptera closes the
Pharynx, and is an appendage of its upper mar-
gin ^

b Hypopharynx (the Hypopharynx). An appendage

» Plate VII. Fig. 2, 3, e'.— What is here called the Lingua in
Ht/menoptera has been usually regarded as the Labium; but surely that
organ which collects, and as it were laps the honey, and passes it
down to the Phanjruc, is properly to be considered as the tongue.
The Labium itself appears to be represented by what has been called
the Menium, and the true Mentum, as was lately observed, is at the
base of the part last mentioned, in the usual situation of that piece.
This, though long since noticed (Kirby Mon. Ap.Angl. i. ]0o— ),ha8
not been much attended to by modern entomologists.
Huher Foumm, A — .

' Plate VII. Fig. 2, 3. and XXVI. Fig. 28. i".
Plate \1I. Fig. 14. f.

« Ibid. Fig. 2. k". This is M. Savigny's name for this part. It
has also been called Ejnglossa. Latrcille OrganisaHon Extcrieure det
Insectcs. 185.

360

EXTERNAL ANATOMY OF INSECTS.

of the lower margin of the Pharynx, observable in
JEucera F. *

The seven organs of the mouth above defined, viz. the
Labrum, Labium, the two Mandibulce, the two Maxillae,
and the Lingua, constitute what may be denominated a
perfect mouth, peculiar to those insects that masticate their
food ^. In those that take it by suction, the Trophi, to
adapt them for that purpose, assume a variety of forms,
and should be distinguished by as many appellations. In
almost every case, however, the rudiments or representa-
tives of the above organs have been detected by the elabo-
rate researches of that learned and able zoologist, M. Sa-
vigny^. I shall next subjoin definitions of the principal
kinds of suctorious mouths.

2. Prqmuscis (the Promuscis). The oral instrument of
Hemiptera, in which the ordinary Trophi are re-
placed '1 by a jointed sheath, covered above at the
base by the Labrum, without Labella (Liplets) at
the end, and containing four long capillary lancets,
and a short tongue ^ It includes the Vagina, and
Scalp ella.

a Vide Savigny Mem. sur les Anhn. sans Vertebr. I. i. 12 — .

>> The majority of Hymenopterous insects, though they have the
ordinary Trophi, are not masticators, using their mandibvlte only for
purposes connected with their economy.
' = See his Mevioires sur les Animaiu sans Vertebres, I. i.

•1 I have used this word here and on a former occasion (see above,
p. 29), perhaps not with strict propriety, in the sense of the French
word rewrplaccr, for which wc seem to have no single corresponding
word in oui- language,
' ' Pj.Axii VI. Fig. 7-9.

EXTERNAL ANATOMY OF INSECTS.

361

A Vagina (the Vagina). The jointed sheath of the
Promuscis, representing the Labium in a 'perfect
mouth ^.

B ScALPELLA (the Lancets). Four pieces adapted for
perforating the food of the insect, which when
united form a tube for suction. The upper pair
represent the Mandibular, and the lower the Max-
nice

3. Proboscis (the Proboscis). The oral instrument of
Diptera, in which the ordinary Trophi are replaced
by an exarticulate sheath, terminated by Labella,
and containing one or more lancets covered by a
valve''. It includes the Theca, and Haustelhim.

A Theca (the TJieca). The sheath or case of the Pro-
boscis, representing the Labium in a perfect mouth ^.
It includes the Basis, and Labella.

a Basis (the Base). The whole lower part of the Tlieca,
from the mouth of the insect as far as the Labella,
probably to be regarded as representing the Men-
tum?

b Labella (the Z/p/efe). A pair of tumid lobes, often
corrugated and capable of tension and relaxation,
which terminate the Theca, and perhaps represent
the termination of the Labium ^"^

B Haustellum (the Haustellum). The instrument of
suction contained in the Theca ^. It includes the
Valvula, Cultelli, and Scalpella.

» Plate VI. Fig. 7, 9. b'. " Ibid. c'. = Ibid. d'.

Ibid. VII. Fig. 5. 6. « Ibid. b'. ^ Ibid. Fig. 6. b'.

" Ibid. a. The Labella have been usually thought confined, or
nearly so, to the genus Musca L. ; but they may be traced in all ge-
JUune.Z)i/jto a,i. e. excluding Hippobosca L.

•> Plate VII. Fig. 5. a', c', d'.

362 EXTERNAL ANATOMY OF INSECTS.

a Valvula (the Valvule). A corneous piece which
covers the instruments of suction above, represent-
ing the Lahrum in a perfect mouth

b CuLTELLi (the Knives). The upper pair of the in-
struments of suction, which probably make the first
incision in the food of the insect; they represent
the Mandihulce of the perfect mouth''.

c ScALPELLA (the Lanccts). A pair of instruments,
usually more slender than the CuLtelli^ which pro-
bably enter the veins or sap-vessels, and together
with them form a tube for suction

4. Antlia (the AntUa). The oral instrument of Lepi-

doptera, in which the ordinary Tropin are replaced
by a spiral, bipartite, tubular machine for suction,
with its appendages'!, it includes the Soleriaria,
and Fistula.

A Solenahia (the Solenaria). The two latei-al subcy-
lindrical air-tubes of the Atitlia

B Fistula (the Fistula). The intermediate subqua-
drangular pipe, formed by the union of the two
branches of the Antlia, which conveys the nectar
to the PhavT/nx'. These two branches represent
the Maxilla of the perfect mouth.— N. B. M. Sa-
vigny discovered the rudiments of the remaining
Trophi in this kind of motith ^.

5. RosTRULUM (the Bostrulum). The oral instrument

a Plate VII. Fig. 5, 6. a'. Mbid. C.

c Ibid d'. It has not vet been satisfl^cto^ly ascertained, whether
.// the ordinary Trophi are represented in every Dipterous mouth,
the number of the lancets seeming in some cases to vary.

..p.,vrrVI.F>a.l3. ; Ibu • - , I^id.

' Ibid. Labrum a'; Mandibulac c; MaxiUary I alpns h .

EXTERNAL A.NATOMV OK INSliri'S.

363

of Aphaniptera {Pulex L.), in which the ordinary
Trophi are replaced by a bivalve beak, between the
valves of which there appear to be three lancets
It includes the Lamitice, Scalpella, and Ligula.
A Lami^je {the Laminae). Two corneous plates which
are laterally affixed to the mouth of a flea, proba-
bly representing the Matidibulce of the perfect
mouth, which somewhat resemble the beak of a
bird ^.

B Scalpella (the Lancets). The two upper or outer
instruments, probably for making an incision in the
- skin ; these are flat and acute, and seem to repre-
sent the Maxillce of the perfect mouth ^

C Ligula (the Ligula). A capillary instrument between
the lancets; probably representing the totigue of
the pei'fect mouth

6. RosTELLUM (the Rostellum). The oral instruments
o( Pedicidus and some other Apter a, in which the
ordinary Trophi are replaced by an exarticulate re-
tractile tube, which exerts a retractile siphuncle.
It includes the TnhuUis and Siphunadiis,

A TuBULus (the Tuhdet). The tube or retractile base
of the Rostcllmn.

B SiPHUNCULus (the SipJmncle). The real instrument
of suction, which when unemployed is retracted
within tlie tubulet.

Besides the above variations from the type of Xfhat I
call a Perfect Mouth, there are others in which the parts
of the Trunk appear to aid in the conversion qfthefood^

' Plate VII. Fig. S. h Ibid. c'.

^ Ibid. d'. Maxillary Tulpi h". <i ibid, e'!

364 EXTERNAL ANA'l'OMY OF INSECTS.

and become a kind of accessory Labium, Maxilla, S,-c.
Thus in the Myriapods, the anterior pair of legs assume
a Maxillary /om and office^', the Prosternum //wse of a
Labium'^: in Arachnida, also, the anterim- Coxas are
accessory Maxillffi. In this Class, likewise, as has been
more than once observed- , the representatives of the inte-
rior pair of Antennae of the Crustacea, are thought
to assume the form and the functions of suctorious Man-
dibles

ii. Facies (the Face). The upper surface of the head =.
It includes all the parts that lie between its junction
with the Prothorax and the Labrum: viz. Nasus,
Postnasns, Frons, Vertex, Occiput, Gence, Tempora,
Oculi, Stemmata, and Antennts.
1 Nasus (the Nose). That portion of the face, often
elevated and remarkable, situated between the La-
brum, Postnasus, and Gencc, and with which the
Labrum articulates; called by Fabricius the Cly-
peus ^ It includes the Bhinarium.
A Rhinakium (the Nostril-piece). The space between
the anterior margin of the Nasus and the Labmm,
in which, in vertebrate animals, the nostrils are often
situated s.— N. B. This is remarkable in some La-
mellicm-n beetles, as Anoplognathus Leach. In Ne-
crophorus, and some others, it is membranous.
2 Postnasus (the Postnasus). That part of the Face
immediately contiguous to the Antenna:, that lies

. Plate VII.Fig. 11, 13./'. ^^-^'^-^l-f-,.

\ 1Q A^r PlateVI. Fig. lU. c.

See above, p. lo. ^ f n ; i ,

•Plate VI. Fig. 1,4, 10. a. ^ Ibul. a.

' Ibid. g'.

EXTERNAL ANATOMY OF INSECTS.

365

behind the Nas7is, when distinctly marked out. —
Ex. Sagra, Prosopis.

3. Frons (the Front). That part of the Face which

lies behind the Postnasus, and usually between the
posterior part of the eyes. This is sometimes the
region of the Stemmata ; or they are partly in this
or pai-tly in the Vertex ^.

4. Vertex (the Vertex). The horizontal part of the Fa-

des, next the front, that lies behind the eyes and
between the temples This also is often the region
of the Stemmata.

5. Occiput (the Occiput). The back part of the head

when it is vertical, or nearly so, to its point of junc-
tion with the trunk — Ex. Meloe, RipipJioritSi
Hymenoptera, Diptera.

6. GENiE (the Cheeks). Those parts which lie on the

outside of the anterior half of the eyes, and inter-
vene also between them and the Mandibnlce ^.

7. Tempora (the Temples). Those parts which lie on

tlie outside of the posterior half of the eyes, between
which the Fro7is and Vertex intervene ^

8. OcuLi Eyes). The principal organs of sight,

most commonly two in number, placed in the sides
of die head. In the majority they are compound,
consisting of hexagonal lenses. In the Arachnida
they are simple ^
A Canthus (the Canthus). A process of the face, which
enters the notch or sinus of the eye e.— Ex. Scara-
bceus L., Cerambyx L.

9. Stemmata (the Eyelets). Two, or more commonly

e n"-.? " 11^' J- ^- ' Ibid. e. « Ibid. f.

g- f Pi-ATEs VI. VII. and XXVI. Ii.

' Plate VI. Fig. 1. and VII. Fig. 2. h'.

366 EXTERNAL ANATOMY OF INSECTS.

three, convex, crystalline, simple eyes, observable
in the Frons or Vertex^ or common to both ». — Ex.
Orthoptera, Heiniptera, Hymenoptera.
10. Antennae (the Antennce). Two moveable and joint-
ed sensilerous organs, situated in the space between
or before the eyes, but in no instance behind them".
They include the Tomlus, ScapnSy Pedicellus, and
Clavola.

A ToRULUS (the Bed). The cavity or socket in which
the base of the Anteima is planted

B ScAPUS (the Scape). The first and in many cases the
most conspicuous joint of the Antenna;'^. It in-
cludes the Bulbus.

a Bulbus (the Bidb). The base of the Scapus, by which it
inosculates inthe Toridus.o^t^n subglobose, and look-
ing like a distinct joint ^ It acts the part of a Rotida,
betng the pivot upon which the Antenna turns.

C Pedicellus (the Pedicel). The second joint of the
Antenna ' : in some insects acting also the part ol a
Botula in the socket of the Scapus, to give separate
motion to the Clavola.

D Clavola (the Clavolet). The remaining joints of the
Antenna taken together^. Itincludes the CapUtdnvu

a Capitulum (the Knob). The last joints of the Cla-
vola when suddenly larger than the rest^.

iii. SuBFACiES (the S«i/ac.). The lower surface or under-
side of the head It includes the Lora and Jugxdum.

« P.ATEVI. Fia. 4, 10. VII. Fio. 1.2. 4.andXXVI.FiG. .-59-41.1.

Plates XI. XII. and XXV.
c Plate VI. Fig. 1, 2. ancl VII. Fig 1. 1 .
Mbid.XII.FiG.«,0.k'. Mbuir. -Ib-d.'.

8 Ibid. Fig. 6. ni'. Mbul. Fic 6. 8-10. m .

i Pr.ATK Vf. Fio. ^i, 8. c.

KXTERNAL ANATOMY OF INSECTS. 357

1. LoRA (the Lorn). A corneous angular machine ob-

servable in the mouth of some insects, upon the in-
termediate angle of which the Mentum sits, and on
the lateral ones the Cardines of the Maxillce and
by means of which the Trophi are pushed forth or
retracted Ex. Hymenoptera.

2. JuGULUM (Uie Throat). That part of the subface

that hes between the temples ^

iv. CoLLUM (the Neck). The constricted posterior part
of a pedunculate head, by which it iiiosculates in
the trunks. It includes the Nucha, Gula, and
Myoglyphides.

1. Nucha (the Nape). The upper part of the neck''.

It includes the Myoglyphides.
A Myoglyphides (the Muscle-notches). Notches in the
posterior margin of the neck, usually two in num-
ber, observable in Coleopterous insects, to which the
levator muscles are attached

2. Gula (the Gula). The lower part of the neck ^

V. C^^nAhovunAoyix{thi,Cephalophragm). A Y-shaped
partition that divides the head internally in Locusta
Leach, into two chambers, an anterior and posterior.

II. TRUNCUS (The Trunk).
The Trunk is the intermediate section of the body
which lies between the Head and the AbdomenK It in-
cludes th€ Manitrunczcs, and the Alitrmmis k

: pr^??- ^ vr. P.O. .^o'"'-

. mT; . • ^' XV'- 4. «• B.

M. ehabner, ,u his admirable Mh„oires sur le Vol des Insecle,,

368 EXTERNAL ANATOMY OF INSECTS.

i. Manitruncus (the Manitrunk). The anterioi- seg-
ment of the trunk, in which the head inosculates, or
on which it turns \ It includes the Prothorax and
Antepectus.

1. Prothorax (the Prothorax). The upper part or
the shield of the manitrunk, in Coleoptera, Ortho-
ptera, &c. called by way of eminence the Tho-
rax^. It includes the Ora, Patagia, Uvibones, and
Phragma.

A Ora (the Ora). The inflexed or inferior lateral mar-
gin of the Prothorax, separated in many genera
from the Antepectus by a suture

B Patagia (the Patagia). Two corneous scales ob-
servable in Lepidoptera, fixed on each side of the
trunk, just behind the head, and covered witli a
long tuft of hair

C Umbones (the Bosses). Two moveable bosses sur-
mounted by a spine, with which the Prothorax of
the Coleopterous genus Macropus is armed.

D Phragma (the Phragm). The Septum that closes
the posterior orifice Prothorax in Gnjllotalpa

Latr.

2. Antepectus (the Forehreast). The underside or
breastplate of the manitrunk, and the bed of the
Arms \ It includes the Spiracula Antepedoralia,
Prosternum, Antefurca, and Brachia.
A Spiracula Antepectorali A {the Antepectoral Spira-
cles). A pair of breathing-pores fixed in the mem-
uses the term T,-onc Alifcrc, which suggested the terms here em-

''?ptxETX.F:a.3, 12,16,&c. ^ Ibid.Fio. 1.2 10, 11, &c.
« Ibid. Fig. 2. a'. " Ibid. IX. Fio. 4.

« Ibkl. VIII. Fig. 3, 11.

EXTERNAL ANATOMY OF INSECTS. 369

brane that connects the Antepectus with the Medi-
pectus *.

B Prosternum (the Forehreast-bone). A longitudinal
or other elevation of the Antepectus between the
Brachial.

C Antefurca (the Antefurca). An internal Vertical
process of the Antepectus^ consisting usually of two
branches, which afford a point of attachment to
muscles of the Brachia

r> Brachia (tlie Arms). The fij st pair of legs of Hex-
apods, the direction of which is usually towards the
head; when spoken of with the other legs, called
the Forelegs ^. They include the Clavicula, Scapula,
Humerus, Cubitus, and Manus.

a Clavjcula (the The first ]omtoHheBra-

chium, answering to the Coxa in the legs.

b Scapula (the Scapula). The second]omt of the Bra-
chium, answering to the Trochanter in the legs.

c Humerus (the Humerus). The third and elongated
joint of the Brachium, answering to the Femur in
the legs.

d Cubitus (the Cubitus). The fourth and elongated
joint, answering to the Tibia in the legs. It includes
the Coronula and Calcaria.

A Coronula (the Coronula). A coronet or semicoro-
net of spines, observable at the apex of the Cubittcs

I p'^^^ O. ^ Px,ATE VIII. FXG. 2, 11. cl'.

Plate XXII, Fig. 7. e'.

. ' ^^.^.y^^^^' i° his Organisation Exterieure des Insectes {Mem.
auimis viii. 198.) proposes calling the forc-lcgs of Hexapods Pro-
pedes; but havmg long ago applied this term to the false legs of ca-
terpillars (see above, Vol. II. p. 288. &c.), we shall not adopt it.
VOL. III. • 2 3

370 EXTERNAL ANATOMY OF INSECTS.

or Tibia of some insects.— Ex. DilopJius Latr.,
Fulgora L.

B Calcaria (the .Sp«rs). See the definition under P.r/^'s

Postici. They include the Velum,
a Velum (the Vehmi). A membrane attached to the

inner side of the cubital spur in Apis L.
e Ma^vs {the Hand). The terminal jointed portion of

the Brachiuvi, answering to the Tarsus in the legs K

It includes the PulviUi, Pahna, and Digitus.
f PuLViLLi (the Pulvilli). See definition under Pedes

g Palma (the Palm). The first joint of the Manus,
when longer and broader than the subsequent ones,
or otherwise remarkable ; answermg to the Planta

in the legs ^ „ 7
A Digitus (the Finger). See definition under Pedes

Postici. It includes the Ungula.
a V^avj^A {the Claw-joint). See definition under P.J.^
Postici. It includes the Pollex, Ungiuadi, and
Palmida.

a PoLLEX (the Thumb). A small accessory jomt, at-
tached to the Ungula of the Manus in ManttsY.
^ Unguiculi (the Clam). See definition under Pedes

y Palmula (the A minute accessory joint

between the claws, answering to the Plantula ui the
leo-s It includes the Pseudonychia.

* Pseudonychia (the Spurious Claws). See definition
under Pedes Postici.

a XXVII. F.o. 36. a: ^ P-tk XV. Fio. 6-9.

^ Plate XXVII. Fic 59. a.

EXTERNAL ANATOMY OF INSECTS. 371

ii. Alttruncus (the Alitrunk). The posterior segment
of the trunk to which the abdomen is affixed, and
which bears the legs and wings ^ It includes the
Mesothorax and Medzpectus, and the Metatliorax
and Postpectus.

1. Mesothorax (the Mesothorax). That segment of
the alitrunk which bears the Elytra, or the anterior
pair of wings, and the intermediate pair of legs
It includes the Collare, Prophragma, Dorsolum,
Scutellum, Frcemmi, and Pnystega.

A CoLLARE (the Collar). Thejirst or anterior piece of
the Mesothorax. In most insects that have a con-
spicuous Prothorax, as the Coleoptera, this piece
appears scarcely to have a representative ; but in the
Libellulina it co-exists with it, and is more con-
spicuous ^ It is particularly remarkable in Hyme-
noptera and Dipta-a.

B Prophragma (the Prophragm). A partition of an
elastic substance, rather horny, connected posteriorly
with the Dorsolum, which passes down into the an-
terior cavity of the aUtrunk, of which it forms the

lol^t'ir'"^* ^' ^' ?' ^' 3> 7, 8,

; ^'^"^i^- 7' 12, 15, 19. g'. The Collare of H.„,eno.
ptera and IhjHera has usually been regarded as representing the
Prothora.v oi Colcoptera, Orthoptera, &c. But this difference obtains
between them-the latter evidently belongs to the Mamtrmik, and
Its muscles do not appertain at all to the AlUrunJc ; whereas the Col-
la,-e as evidently is a part of the latter, its muscles belong to it, and
Its functions in assisting in flight are important. These reasons, and
others we shall state hereafter, induced us long ago to consider this
rllM rrr^'"?"^ P-^^ora.; and they seem to have in-
duced M Chabner almost to adopt a similar opinion. SurleVolde.
Insccles. Ann. du Mus. 3eme Ann. 414. et 4eme Ann. 54-.

2 B 2

372 EXTERNAL ANATOMY OF INSECTS.

upper separation from that of the manitrunk. It
affords a point of attachment to several muscles of
the wings, &c. ^
C DoRsoLUM (the Dorslet). The piece which lies be-
tween the Collare and Scutellum, to which the pro-
praghm is anteriorly attached, and which bears the
upper or anterior organs of flight ^. It includes
the Pteropega, Elytra, Tegmina, Hemelytra, Alee
Superiores, and Tegulce.
a Pteropega (the Wing-socket). The space in which
the organs for flight are planted. That for the se-
condary or under-wings is in the Metatharax^.
b Elytra (the Elytra). The upper organs for flight,
when they are without nervures, and uniformly of
a thicker harder substance than membrane whether
corneous, or coriaceous ; lined by a fine membrane ;
and when closed, united by the longitudmal suture^.
They include the Axis, Sutura, Epipleura, Alula,
and Hypoderma, and are peculiar to the Coleoptera
and Dermaptera.
A Axis (the Axis). A small, prominent, irregular pro-
cess of the base of the Elytrum, upon which it turns,
and by the intervention of which it is affixed to the
Dorsohim, in the anterior wing-socket ^
B SuTURA {the Suticre). The conflux of the sutural or
inner margins of the two Elytra, where when closed
they unite longitudinally ^

a Plate XXII. Fig. 8, 11. A'. . rv i - a

b Ibid. Fig. 8. Plate VUL Fig. 3, 12, U, 16. IX. Fig. 1, /, 8,

10—12, 15, 19, 21. i'. ,xrviT 17 a A"

c P.1te VIII.FiG.14,20. IX.FiG.11,12. and XXII. t.o. 8.6

a Plate X. Fig. 1.; and XXVIII. Fig. 1-8, 10^

^ Plate XXVIII. Fig. 3-5. A'". ^ Plate X. Fig. 1. c .

EXTERNAL ANATOMY OF INSECTS.

373

C Epipleura (the Epipleura). The inflexed accessory
margm observable underneath in many Elytra,
which covers the sides of the alitrunk and abdo-
men *.

D Alula (the Winglet). A small, membranous, wing-
like appendage, attached to the Elytrum on one side
and the Frcenum on the other; which probably
serves to prevent the dislocation of the former —
Ex. Dytiscus. N. B. A similar organ for a similar
purpose is to be found in Blatta and the Diptera.

E Hypoderma (the Hypoderma). The skin, in some
species beautifully coloured, that lines the Elytra
N. B. This skin is also found in some Hemelytra, but
not in Tegmina.

c Tegmina (the Tegmina). The upper organs of flight,
when of a uniform coriaceous or pergameneous tex-
ture, veined with nervures, and lapping over each
other ^. Ex. Orthoptera^,

d Hemelytra (the Hemelytra). The upper organs of
flight, when they are corneous or coriaceous at the
base and membranous at the apex^. — Ex. The
heteropterous Hemiptera. They include the Co-
rium and Membrana.

A CoRiUM (the Corium). The corneous or coriaceous
part of the Hemelytrum s.

Plate XXVIII. Fig. 6-8. d"\ b p^.^^^ XXIII. Fig. 6. e".
' Plate XXVIII. Fig. 2.
^ Ibid. Fig. 19. and Plate X. Fig. 2.

" The upper organs of flight of many of the homoptcrous section
ol the Hemiptera seem altogether membranous, and may almost be
included under the term Ala; Supenores.

' Plate X. Fig. 3. « Ibid./'".

374 EXTERNAL Al«i ATOMY Ol- INSECTS.

B Membrana (the Membrane). The membranous part
of the same

e Alje SurERiORES vel Primarije (the Upper or Pri-
mary Wings). The upper or anterior organs of
flight when formed of membrane, or of the same
substance with the under-wings They include
the Axes, Area, Areolcs, Neurce, Stigma, Parastigma,
and Lohuli.

A Axes (the Axes). Several osseous or horny pieces,
by which the wing is connected with the Dorsolum".
One usually to each area.

B AREiE (the Areas). The larger longitudinal spaces
into which the wing may be divided They in-
clude the Area Costalis, Intermedia, and Analis.

a Area Costalis (the Costal Area). That part of the
wing lying between the anterior margin and the
post-costal nervure^ In Hymenoptei-a and Di-
ptera it includes all the space bounded by the ner-
vures that spring from the postcostal.

b Area Intermedia (the Intermediate Area). That
part of the wing lying between the costal area and
the interno-medial nervure, in Diptera ; or the
Anal in Orthoptera, Hemiptera, Hymenoptcra, &c. ^
p Area Analis (the ^waZ ^rm). All that part of die
wing which in Diptera lies between the interno-

a Plate X. Fig. 3, g" ,

b Ibid. Fig. 5—9, 11-15. and Plate XXVIII. Fig. 18.

<■ IbidJi". ^. ^ ..^

.1 N.B. In the Plate the Costal Area is red, the Intermediate white,
find the Anal yellow. When the llemehjlra are considered as divuled
into Areas, the Membrana might be denominated the Apieal Area.
' Plate X. Fig. 2. 3, 6-. ' ^bid.r'.

EXTERNAL ANATOMY OF INSECTS.

375

media] nervure ; oi' in Orthoptera, &c. between tlie
anal nervure and the posterior margin

C AnEOLiE (the Areolets). The smaller spaces into
which the wing is divided by the nervures. They
include the Areola Bas'dares, Media, and Apicales.

a Areola Basilares (the Basal Areolets). The pa-
rallel areolets of the base of the wing''.

b Areolte Mediae (the Middle Areolets). The areolets
of the wing that lie between the basal areolets and
the apical

c Areola Apicales (the Apical Areolets). Tliose
areolets of the wing that termmate in or very near
the apex ^.

D Neur^ (the Nej-vures). Corneous tubes, for expand-
ing the wing and keeping it tense, and to afford
protection to the air-vessels — commonly called the
Nerves. They include the Neura Costalis, Post-
costalis, Mediastina, Externo-media, Interno-media,
AnaliSf Axillaris^ and Spuria. '

a Neura Costalis (the Costal Nervure). The first
principal nervure of the wing, close to or forming
the anterior margin in Lepidoptei a, Hymenoptera^
and Diptera; but sometimes remote fi-om it in Teg-
mina ^. It includes the Phialum and Hamus.

u Phialum (the Phial). A little bag to receive fluid at
the will of the insect, by which the weight of the
wing is increased. It is found also in the under-
wings in Coleoptera ^ ,

=• Plate X. Fig. 2, 3. d: ' b ibid. Fig. 7—15. e\

" Ibid./. u Ibid, g., c Ibid. h-.

' Chfibrier Sur le Vol des Insecles, Ann. die Mas. Seme ann. 4i'8,
4cine ann. 325—. 3cl Cahier 78.

376 EXTERNAL ANATOMY OF INSECTS.

jS Hamus (the Hook). A Hook fixed to the Costal
Nervure, near its base on the under-side, in the
wings of some Lepidoptera, in which the tendon
runs ^.

b Neura Postcostalis (the Postcostal Nervure). The
second principal, and often strongest, nervure of
the wing ^. It includes the Neura Suhcostales.
a. NEURiE SuBCOSTALES (the Subcostal Nerimres). Ner-
vures springing from the under-side of the post-
costal nervure, or from each other ; called the Jirst,
secofid, third, &c. in the order of their occurrence
c Neura Mediastina {Mediastinal Nermre). A. usu-
ally slender nervure, springing from near the base
of the postcostal ; between which and the costal it
intervenes. In the Lepidoptera Diurna, however,
it is often a strong nervure ^.
d Neura Externo-media (the Externo-medial Ner-
vure). The third principal nervure of the wing ^.
It includes the Neura Subexterno-media.
a Neura Subexterno-media (the Subexterno-medial
Nervure). A nervure that in some cases intervenes
between the externo-raedial and interno-medial
e Neura Interno-media (the Interno-medial Nervure).
The fourth principal nervure It includes the
Neura Subinter7io-media.
a Neura Subinterno-media (the Subinterno-medial
Nervure). A nervure that sometimes intervenes
between the externo-medial and the anal''.

» Linn. Trans. \. t. xiii./. 2. 3. d. Plate X. Fig. 5—15. r.

'Ibid. fl*. Mbid. Fig. 6. -t-. ''Ibid./-,

f Ibid. Fig. 5, 6, 13. i*. * Ibid. Fig. 5—15. m\
» Ibid. Fig. 5, 6,13.c*.

EXTERNAL ANATOMY OF INSECTS.

377

f Neura Analis (the Anal Nervure). The principal
nervure nearest the interior or posterior margin,
with which it includes a space often subtriangular,
traversed in most Diptera and many Hymenojjtera
by another nervure; and in many Tegmina and
Hemelytra by several ». In these kinds of upper-
wing it is in many cases accompanied by a fold; and
the part between it and the interior margin seems
often capable of separate motion.

g Neura Axillari s (the Axillary Nervure). The short
nervure, where there is only one, intervening be-
tween the anal nervure and the interior margin ;
replaced in some Muscidce by a spmious ner-
vure

h Neur^e SpuRiiE (the Sjmrioiis Nermres). Very ob-
solete nervures, sometimes found in addition to
those^ usually occurring; as in Syrphus'^.

E Stigma (the Stigma). A corneous spot or plate, sup-
posed to contain fluid, in the anterior margin of the
upper wings; often produced by the conflux of the
costal and postcostal nervures ^.

F Parastigma (the Parastigma). A corneous spot be-
tween the costal and postcostal nervures, distinct
from the Stigma observable in the Libellulina.

G LoBULi {Lobuli). One or more rounded portions of
the base of the wing, separated from the rest by fis-
sures peculiar to the Muscidce, and the under-wings
of some Hymenoptera ^.

f Tegul^e (the Tegulcc). Small corneous concavo-con-

Plate X. Fig. 5-15. n: " Ibid. o-.

Mbicl.FiG.14.;r. H Ibid. Fig. 11.. r.

Ibid. Fig. 14,15. «"'.

378 EXTERNAL ANATOMY OF INSECTS.

vex scales, which in many Orders, particularly Hy-
vienoptcra, cover and defend the base of the Uprcr-
Whigs \

D ScuTELLUM (the Scutellum). A piece, usually tri-
angular, which follows the Dorsolum; and in Co-
leoptera is often only a continuation of it— placed
between the base of the Elytra or upper-
wings

E Fr(ENUM (the Frcenum). A piece that lies under the
lateral margin of the Scutellum and Dorsolurm or is
adjacent to it; and which in many cases connects
with the base of the upper organs of flight, so as to
prevent their dislocation, by being pushed too far
outwards ^

F Pnystega (the Pnystega). A corneous scale or plate,
which covers certain pneumatic vessels, usually
supported by i\\e Scapularia, in Libellulma, &c. be-
coming dorsal

2 Medipkctus (the M«r.asO. The underside of the
first segment of the alitrunke. ^ includes the
Peristethium, Scapularia, Mesosternum, Medifurca,
and Pedes Intermedii.

A Peristethium (the PeristetMum). The anterior
piece of the Medipectus, which intervenes between
the Brachia and mid-legs ^,

B ScAPULARiA (the Scapidars). Two pieces, one on
each side the Medipectus, which succeed the Peri-
stethium, and he between the midlegs and the Pte-

a Plate IX. Fig. 5. ll.g . p,^,, yx. Fig. 7-
:p;l-iviII.FiG.4,13. 17.; and IX. Fig. 3. 8, 13...
f Ibid. /('.

EXTERVAI. ANATOMY OF IN8ECT«.

370

roppffu or win^-socket^ It includes the SpiracuUi
Scajmlaria.

-.1. .Si'iiiACULA ScAi'L'LAiUA (the Scajmlur Spiracles).
Two Hpiracles ol)serv,'il)le, one in each scapular, in
Acrida lauri/'olia, &c.

C Mesosternum (the Mid-ln-easlonc). 'Yha elevated
and central part of the Mcdipeclm, between the mid-
legs, often terminating anteriorly in amucro; some-
times, as in Elaler, in a cavity, receiving the mu-
cro of the Prostermcm ''.

J) Mi:nn-LncA (the Mcdifurca). A branching vertical
j)rocess of the Endoslernuvi^ whicJi .serves as the
point of attachment to the muscles that move the
mid legs

E Pedes Inteiimeoii (the MV/-/i?^/,v). The intermediate
pair of legs, consisting of the same parts as the
posterior legs

.'i. Metatiioiiax (the Melalhorax). The posterior seg-
ment of the Alilruncm". It includes the Meso-
phragma, Posldursolum, Postscutellum, Poatjrccnum^
PlmrcE^ and Melaphragma.

a Mesoi'hracma (the M?5ty7>^ra^rOT). A partition of a
firm consistence, connected by its posterior margin
with the Postdor solum, and passing down vertically
into the mid-chest; serving as a point of attjjch-
ment to several of the muscles that move the
whigs ^ This, with the prophragm, forms the an-

' Pi-ATKs VIII. IX. ,/. >' Platk VIII V,,.. 4, 8, 1.3, I7. ,/

« P1.AT1; VIII. Vu;. 3. 12,; and IX. Fi.;. 1, 7, 10, J J, 12
15. c, '

' Pi-atlXXII. Fio. 9, 11. ,'.

380

EXTERNAL ANATOMY OF INSECTS.

tei-ior cavity of the alitrunk, and with the meta-
phragm it forms the posterior cavity.
) PosTDORsoLUM (the Postdorsolum). The middle- .
piece between the mesophragm and the Fosiscti-
tellum. In Coleoptera it consists of a tense elastic
membrane, which is quite covered by the Meso-
thorax

3 PosTSCUTELLUM (the Posto^eZte). A narrow chan-
nel running from the Dorsolum to the Abdo^nen in
Coleoptera, forming an isosceles triangle reversed.
In other orders it is either a triangular elevation of
the middle of the posterior part of the Postdorsolum,
or a distinct triangular piece
d PoSTFRCENUM (the Postfrcenum). In Coleoptera the
part of the Metathorax in which the Postscutellum
lies, at first nearly horizontal, but posteriorly it takes
a vertical direction towards the abdomen. In ge-
neral it may be defined, the part that intervenes
between the Postscutellum and the Abdomen ; and
which in many cases is connected with the posterior
basal margin of the under- wings, and prevents their
being pushed too far forwards
e Pleura (the Pleurce). The space behind the scapu-
lars, on which the lower organs of flight are fixed
They include the Ales Inferiores.
A ALiE Inferiores (the Under-wings). The lower or
secondary pair of organs for flight They include
the Commiss7ira, Tendo, Hamidi, Pteiygium, Alula,
and Halteres.

' Plate VIII. Fig. 3, 12, 20. and IX. Fig. 7, 10-12, 15,20. f.
b Ibid. u. ' Pi-'^'^J^s VIII. IX. XXVIII V.

o Plates VIII. and IX. »''. ' Plate X. Fig. 4, 10.

EXTERNAL ANATOMY OF INSECTS.

381

a CoMMissuRA (the Commissura). A joint in the costal
nervure of the wings of Coleoptera, where they bend
to take a ti*ansverse fold ^.

b Tendo (the Tendon). A strong bristle, or bristles
observable at the base underneath in the under-
wings of many Lepidoptera, which plays in the Ha-
mus of the upper-wmgs

c Hamuli (the HooH^ifs). Very minute hooks in the
middle of the anterior margin, observable in some
Hi/menoptera, by which the under-wing is fixed to
the upper, to cause both to act as one organ in
flight

d Pterygium (the Pteiygium). In under- wings this is
a small wing-like appendage, fixed at the base of
the wing in some Lepidoptera ^.

e Alula (the Winglet). A small concavo-convex sca-
rious appendage, fixed behind the wings at their
base, in many Dipt era

/ Halteres (the Poisers). Small capitate processes or
organs, observable under the wings of Diptera, at-
tended by a spiracle ^.

B Metapnystega (the Metapnystega). A corneous
scale or lamina that covers the pneumatic organs
in the Metathorax, situated sometimes in the Pleu-
rce, as in the Coleoptera; at others in the Postfrce-
num, as in Tenthredo L.; and sometimes, as in the
Lihdlidina^ between that part and the abdomen ^.

» Plate X. Fig. 4. o'". Linn. Trans, i. t. xiii./. 1. i. 3. a.

" Kirby Mon. Ap. Angl. i, /. xiii./. 19.

De Geer ii. /. ix./. 9. d. « Ibid. vi. t. W.f. 23. a a.

f Plate IX. Fig. 19. p ".
^ Ibid. Fig. 7. and Plate XXII. Fig. 14. k" .

382 EXTERNAL ANATOMY OF INSECTS.

C Metaphragma (the Metaphragm). A nearly verti
cal septum or partition, attached behind to the
Postfroenum, and usually deeply cleft at its apex in
Coleoptcra, of a rather horny consistence, which
forms the upper separation of the second cavity ol
the Alitrunk from that of the Abdomen^. It affords
a point of attachment for many muscles of both
alitrunk and abdomen. It includes the Septula.

a Septula (the Septula). The lesser ridges and par-
titions raised on the surfaces of the metaphragm,
and on those of other parts of the cavities of the
trunk, serving as points of attachment to various
muscles ^.

4-. PosTPECTUS (the Postpectus). The underside of the
second segment of the ahtrunk ^. It includes the
Mesostethium, Parapleurce, Metasternum, Postfiirca,
Opercular and Pedes Postici.

A Mesostehium (the Mesostethium). A central piece
between the intermediate and posterior legs, and
bounded laterally in Coleoptera by the Parapleura
—along the middle of which, where it exists, the
Metasternum runs ^.

B PARAPLEURiE (the Parapleural). Two pieces, one on
each side of the Postpectus, included between the
Scapularia, Mesostethium, and Pleura ^ They in-
clude the Spiracula Parapleuritica.

a Spiracula Parapleuritica (the Paraplcuritic Spi-
racles). Two spiracles, one in each of the Para-
pleurcE of Tetyra ^

^ Plate XXII. Fig. 10, 11. x. » Ibid. Fig. 9-11./".

c Plates VIII. and IX./. " Ib'd- ^ •

, jj^jj „, < Pi.ATF. XXIX. Fig. lo. ?H .

EXTERNAL ANATOMY OF INSECTS.

383

C Metasteunum (the Metasicrnum). The central and
often elevated part of the Mesostethium. Its anterior
mucro, in Coleoptera, often meets the posterior one
of the Mesosteymum, and sometimes appears to form
one piece with it, as in Hydrophilus, and many
Lamellicorn beetles. Sometimes, as in Cetonia vit-
ticollis, it even passes betvreen the arms^ and covers
the Prosternum, or supplies its place. Behind, it
often terminates in a bifid mucro. It is not present
in many Orders : as in the Hymenoptera, Diptet'a,
&c. ^ It mcludes the Pectines.

a Pectines (the Pectines). Two moveable processes,
fixed one on each side by its base below the posterior
legs to theMetastemum in Scorpio: on the lower side
is fixed a series of parallel biarticulate processes, re-
sembhng the teeth of a comb

D PosTFURCA, (the A process of the i^w-

dosternum, terminating in three subhorizontal acute
branches, resembling the letter Y, and forming an
acute angle with the Endosternum, to which the
muscles that move the hind-legs, &c. are affixed

E Opercula (the Opermla). Plates that cover the
vocal spiracles in humming insects ; and likewise
two large cartilaginous plates fixed to the posterior
part of the Postpectus, which cover the Tympana
in male Tettigonia F. ^ Perhaps tliese may be re-
garded as a kind of Metapnystega in a new situ-
ation.

F Pedes Postici (the Hind-legs). The pair of legs

» Plates VIII. IX. a f. " Plate XXVII. Fig. 50.

Plate XXII. Fig. 3. if-
" Plate VIII. Fig. 18 ; and XXII. Fig. 13. cf.

384; EXTERNAL ANATOMY OF INSECTS.

affixed to the postpectus \ They include, the Ace-
tabuhm, Coxa, Trochanter, Femur, Tibia, and
Tarsus.

a Acetabulum (the Socket). The socket in the Post-
pectus in which the leg is planted ^ It includes the
Pessella.

A Pessella (the Pessdla). Two little acute processes,
fixed one in each, in the socket of the hind-legs in
male TettigonicB, which appear designed to keep
down the Opercula

b Coxa (the Hip). Thejirst joint of the leg which
plays in the socket^.

c Trochanter (the Trochanter). The second joint of
the leg, by which the thigh inosculates in the Coxa.
It appears to have no motion separate from that of
the thigh. It is sometimes biarticulate ^

d Femur (the Thigh). The third joint of tlie leg, long
and usually compressed It includes the Gony-
theca.

A GoNYTHECA(thei^we<?-paw). A concavity at the apcx
of the thigh, imderneath, to receive die base of the
Tibia s.

e Tibia (the Shank). The fourth joint of the leg, very
long, and usually triquetrous \ It includes the
Epicnemis, Molula, Talus, Calcaria, and Coro-
nula.

a Plate XIV. Fig. 5-8.

^ Plate VIII. Fig. 3, 4, 11, 13, &c. o". ^ Ibid. Fig. 18. 9 •
a Plate XIV. Fig. 0-8; and XXVII. Fig. 12. p". ' Ibid. ? .
' Plate XIV. Fig. 5-8; and XXVIl. Fig. 6-8. r" .
s Plate XXVII. Fig. 7, 8, 15. r" .
h PlateXIV. Fig. 5— 8.*".

extehnal anatomy of insects. 385

A Epicnemis (the Epicnemis). An accessory joint at
the base of the Tibia in many Arachnida, which
does not appear to have separate motion ^.

B MoLULA (the Knee-ball). The convex and sometimes
bent head of the Tibia, armed with a horny pro-
cess on each side, by which it is attached to the
thigh

C Talus (the Ankle). The apex of the Tibia, where it

is united to the Tarsus
D Calcaria (the Spurs). One, two, or more moveable
spines, inserted usually at the apex of the Tibia;
and in many Carabi L., Lepidoptera L., and Tricho-
ptera K., in the middle also. They may be regarded
as a kind of fingers auxiliary to the Tarsus, and fur-
nish often an important character m the disciimina-
tion of genera

E CoRONULA (the Coromda). A coronet or semicoronet
oyixed spines observable at the apex of the poste-
rior Tibia m Fulgora candelaria, &c.

f Tarsus (the Tarsus). The ffth principal portion
of the legs-; consisting in the majority of msects of
1—5 joints, but in the Phalangida of sometimes as
many as 50 ^ It includes the Planta, Digitus, and
Solea.

A Planta (the Instep). The first joint of the Tarsus is
so called when it is remarkably long and broad
It includes the Calx.

: ^^^^i^^::^:'"- "

I Plate XIV. Fig. 6j and XXVII. Fig. 29-36.

f Plate XXVII. Fig. 25, 26, 41. w'".
VOL. III. 2 c

386 EXTERNAL ANATOMY OF INSECTS.

a Calx (the Heel). The curvmgpart of the Planta, by
which it inosculates with the Tibia.

B Digitus (the Toe). The remaining joints of the Tar-
sus taken together ». It includes the Allux and Vn-
gula.

a Allux (the Toe-ball). The last joint but one of the
Tarsus, when remarkable, as in Rhyncophorous
beetles {Curculio h.)^.
b Ungula (the Clana-joint). The last joint of the Tarsus,
which bears the claws It includes the Arthrium,
Unguiculi, and Plantula.
a Arthrium (the Arthrium). A very minute joint at
the base of the claw-joint, in most Tetramerous and
Trimerous beetles ^.
|3 Unguiculi (the CZflTOs). One or two pair of moveable
incurved claws, which usually arm the apex of the
Ungtila ^.

y Plantula (the PZaw^M^a). A minute accessory jomt,
sometimes attached within the claws to the apex of
the Ungula Ex. The Lucanidce. It includes the
Pseudonychia.

* Pseudonychia (the Spurious Claws). Two stiff claw-
like bristles, that terminate the Plantula s.

C Solea (the Sole). The underside of the TarsusK It
includes the PulvilU.

a PuLViLLi (the Pidvilli). Cushions of short hairs very
closely set; or of membrane, capable of bemg m-

a Plate XXVII. Fig. 25, 26. .r"'.

u LteXXVI.Fig.47, 48. ^^V" Fig^43. .^

e Pl^te XXVII. Fig. 37-57. e*. Ibu • Fig. 50, •>/./ •

.Ibid. Fig. 56..^. Mbid. Hg. 59.,/ .

EXTERNAL ANATOMY OF INSECTS.

387

flated, or very soft ; or concave plates, which cover
the underside, or their apex, of the fom- first joints
of the Mantis or Tarsus, and sometimes even of the
ends of the Calcaria, as in Cimbex; which act so as
to produce a vacuum, and enable the animal to sus-
pend itself, or walk against gravity a. Ex. Timar-
cha, BuprestiSi Prioca^a K., the Gryllina, Musci-
dce, &c.

III. ABDOMEN (the Abdomen).
The Abdomen is the tJiird or posterior section of the
body which follows the Truncus ^. It includes the Ter-
gum. Venter, Petiolus, Cauda, and Amis.

u Tergum (the Tergum). The upper or supine surface
of the abdomen It includes the Segmenta Dorsa-
lia, and Pulmonaria.

1. Segmenta DoRSALi A (the Z)or5aZ5f^^»2eM^5), Trans-

verse segments of the back, the sides of which often
lap over and cover those of the ventral segments

2. Pulmonaria (the Pulmonary Space). Two longitu-

dinal soft spaces, capable of tension and relaxation,
one on each side of the back of the abdomen, in
which, where they exist, the dorsal spu-acles are
planted ^ They include the Spiraada Dorsalia.
a Spiracula Dorsalia (the Dorsal Spiracles). Late-
ral breathing-pores observable m the dorsal seg-
ments, often covered by the precedmg segment

' ^"-^^^ Fig. 9 ; and XXVII. Fig. 35, 59-61. t:

P':ATB Vni.FiG. 5,6,9,15, 18,19.
Mb.d.PiG.5,15.^. d Ibid ^'

Mbid. Fig. 5, 9. P'. ' Ibid. Fi;. 5, 9, 15.

2 c 2

388 EXTERNAL ANATOMY OF INSECTS.

ii. Venter (the Belly). The lower or prone part of the
abdomen ^ It includes the Hypochondria, Epiga-
strium ^, Scgmenta Veniralia, and Elastes.

1. Hypochondria (the Hypocliondria). Two portions

of segments, one on each side; which in some ge-
nera {Carahus L., &c.) intervene between the first
intire ventral segment and the posterior part of the
Postpectus.

2. Epigastrium {the Epigastrium). The first intire ven-

tral segment''. It includes the Mucro and Tym-
pana.

A Mucro (the Mucro). The central posterior point of
the Epigastrium observable in many of the Orders,
which reposes between the posterior legs ; and, ac-
cordmg to M. Chabrier, is useful to the insect du-
ring flight

B Tympana (the Drums). Two deep cavities, contain-
uig a complex machinery on each side of the Epiga-
strium in male Tettigonia, which are the instruments
of sound ^.

3. SEGMENTAVENTRALiA(theF^wi;raZSe5Wcn/5). Trans-
verse sections of the belly s. In Elytrophorous in-
sects they are usually of a firmer consistence than
those of the back. They mclude the Spiractda Ven-
tralia.

A Spiracula Ventralia (the Ventral Spiracles).—
a Plate VIIT. Fig. 6, 9, Ib.B.

b The scientific reader must recollect that these terms are em-
ployed, not because these parts are thought to be true representa-
tives of the Epigastrium and Hi/pochondria of vertebrate anmu.1.,
but merely on account of some analogy between them.

0 Platk VIII. Fig. 6. Ibid. 2)'. lh,d. i? .

rlbid.F.G.18,19. r. MbKl.F.G. 0,9,1...^.

EXTERNAL ANATOMY OF INSECTS. S89

Breathing-pores observable in some genera in the
intermediate ventral segments, one on each side ».
Ex. Dijnastes Aloeus, &c.

4-. Elastes (the Elastes). The elastic organs on the
ventral segments of Machilis poli/poda which assist
this insect in leaping.

iii. Petiolus (the Footstalk). A slender part by vehich
the abdomen of many Hymenoptera is united to
the trunk, in some genera very long, in others very
short, and in others wanting ^. It includes the Fu-
niciilusy Foramen^ Squama, and Nodus.

1. Funiculus (the Funimlus). A small cartilaginous

cord, passing through a minute orifice of the Post-
frcenum, just above the point where the footstalk is
fixed, to an opposite hole above it, which enables the
animal the better to elevate or drop the abdomen ^.

2. Foramen {the Foramen). The orifice in the abdo-

men, through which the above cord passes

3. SouAMA (the Scale). A vertical flat scale, observable

on the footstalk of the genus Formica, &c. "

4- Nodi (the Knots). One or more subrotund protube-
rances of the footstalk in the genus Myrmica f.

iv. Cauda (the Tail). Where the abdomen grows sud-
denly slenderer, and terminates in a long jointed
tail, as in Scorpio . and Panorpa s. It includes the
Centris.

1. Centris (the C^?;?^m). The last inflated joint of the
tail, terminating in the Sting.

Plate VIII. Fig. Q.D.
" Ibid. Fig. 13. F' .

Ibid. Fig. 17.7/'.
■= Plate XV. Fig. 13. D.

^ Plate IX. Fig. 17, 18. C.

0 Ibid. G'.

' Ibid. Fig. 18. /'.

390 EXTERNAL ANATOMY OF INSECTS.

V. Anus (the Anus). The termination of the abdomen,
consisting of the two last segments. It includes the
Podex, Hypopygium, Cidus, Ovipositor, and ApjJe?!-
dices.

1. PoDEX (the Podex). The last dorsal segment of the

abdomen ^.

2. Hypopygium (the Hypopygium). The last ventral

segment of the abdomen ^.

3. CuLUS (the Cidus). The orifice at the end of the

anus.

4. Ovipositor (the Ovipositor). The instrument of

oviposition, by which the insect conducts the eggs
to their appropriate nidus, and often bores a way to
it; the same instrument is by some genera used as
a weapon of offence, when it is called the Aadeus
It includes the Unci, Tubulus, Valvce, Vaginula, and
Terehell(S.

A Unci (the Unci). Two pair of robust organs, the
upper incurved and the lower recurved, with which
the anus oi Locusta Leach is furnished "i.
B TuBULUS (the Tid}ulus). A tubular ovipositor, con-
sisting of several pieces often retractile withm each
other, like the tubes of a telescope ^
C Valv^ (the Valves). Two lateral laminae, often coria-
ceous, by which the ovipositor when unemployed is
covered ^.

D Vaginula (the Sheath). A corneous case, with

a Plate VIII. Fm. 5, 15. K'. " Ibid. Fig 6, 15, 18. L'.

« Plate XV. Fig. 18-22; and XVI. Fig. 1-3.

•I Plate XV. Fig. 18.

« Plate XV. Fig. 22; and XVI. Fig. 2, 3.

f Ibid. Fig. 20, 21 j and XVI. Fig. 1. F ".

EXTERNAL ANATOMY OF INSECTS.

301

two grooves, in which the Terebella or Sjriada
play \

E Terebella (the Terebellce), Instruments by which
the insect saws or bores a passage for its eggs to the
place in which her instinct directs her to deposit
them

5. AcuLEUs (the Sting). The above instrument, when
fitted for an olFensive weapon It includes, besides
the Valvce and Vagi7iula before defined, the Sjpicula.

A Spicula (the Z)ar/s). The proper stings which inflict
the wound : retractile within the sheath, externally ser-
rulate at the apex ^. They include the Retinaculum.

a Retinaculum (the Retinaculum). A minute horny
moveable scale or plate with which the darts are fur-
nished, which prevents their dislocation by being
shot forth too far

vi. Appendices (the Appendages). Other instruments
and organs, with which the anus of various insects
is furnished. They include— the Forceps, Forfex^
Furca, Styli, Foliola, Flosculus, Caudulce, Fila, Mam-
milla, Papillce, and Siphonuli.

1. Forceps {the Forceps). A pair of anal organs that

open and shut transversely, and meet at their inner
margin, or at the apex. Ex. Forfiada.

2. FoRFEx (the Forfex). A pair of anal organs, which

open or shut transversely, and cross each other K
Ex. Male of Raphidia Ophiopsis.

^ Plate XV. Fig. 20. G '.

" Ibicl. Fig. 20, 21 ; and XVI. Fig. 1. H".

« liirby Mon. Ap. Angl. i. t. xii. Apis **. e. 1. jwui.f. 23—25: and
L xiii./. 27, 28.

^f>id. t. xiii./ 30, 31. « Ibid. a.

' Plax£ XV. Fig. 12. L".

392

EXTERNAL ANATOMY OF INSECTS.

3. FuRCA (the Fork). An inflected elastic anal organ,

ending in a fork, by which the animal is enabled to
leap ^. Ex. Podura.

4. Styli (the Styles). Rigid, exarticulate, long and

narrow anal organs ^. Ex. Staphylijius.

5. FoLiOLA (the Leajlets). Rigid, exarticulate, dilated,

leaf-like anal organs Ex. Lihellulina.

6. Flosculus (the Floret). A small, tubular, lunulate

anal organ, with a central style ^. Fulgora cande-
lariUf &c.

7. Cerci (the Cerci). Two short, flattish, sublanceo-

late, jointed, lateral anal organs ^ Ex. Blatta.—
N.B. Analogous organs are observable in the Gryl-
lina, but usually conical and without joints f. In
Gt-yllus Latr. they are setiform s.

8. CAUDULiE (the CaudulcE). Two or more slender, fili-

form or set2iceovLS, jointed, flexile anal organs*'. Ex.
Lepisma, Machilis, Ephemera.

9. FiLA (the Threads). Two exarticulate, slender, fili-

form anal organs Ex. Machilis.

10. Mammul^ (the Mammulce). Anal protuberances,
containing instruments for spinning web Ex.
Araneidce. They include the i^wsz.

11. Fusi (the Spinners). Organs, consisting of two re-
tractile pieces, issuing from the Mammulce, and ren-
dering the threads

a Plate XV. Fig. 14. M". " Ibid. Fig. 17-

c ibid. Fig. 15. 0". " Md. Fig. 13. P".

« Ibid. Fig. 23. Q". . ^ ^ ....

f DeGeeriii.f.xxu./.10.««. « Ibul. xxiv./. 3. r; and/. 11.

" Plate XV. Fig. 16. R". ' ' ^„

^ Ibid. Fig. 10; and Plate XXIII. Fig. 16, 17- •
1 Ibid. Fig. 13. B'". 15.

EXTERNAL ANATOMY OF INSECTS. 393

12. SiPHONULi (the Siphonets). Truncated, fistular, seti-
form anal organs, emitting a saccharine fluid ^. Ex.
Aphis.

You will observe, that when the iv/iole uppei-side of
the T7 'uncus is spoken of, it is called the Thoi'ax ; and as
in Coleoptera, and some other Orders, the whole of the
Mesothorax except the Scictellum is covered by the TJio-
rax^ and tlie whole of the Metathorax by the MesotJiorax
and Elytra — the Thoracic shield may without danger of
mistake be denominated the Thorax, as it has always
been. When the "dohole under-side of the Tnmh is spo-
ken of, it is called the Pectus. When the three Stermms
are spoken of together, they may be called the Sternum ^
and the ivhole interior- elevation of the Pectus may be
called the Endostermm.

» De Greer ubi supr. I. iii./. 5,20, 21. c.

LETTER XXXIV.

EXTERNAL ANATOMY OF INSECTS.

THE HEAD, AND ITS PARTS.

Before I confine my observations to the head of in-
sects, which I propose to consider separately in the pre-
sent letter, I must premise a few words upon then- bodTj
in general, or rather its crust, or external integmnent.
In this we may notice its substa?ice, general form, sculp-
ture, pubescence, and composition.

i. I have already noticed the substance of this integu-
ment in the preparatory states of insects-; I shall not,
therefore, here repeat what I then said, but restrict my-
self chiefly to the consideration of it as it is found m then-
last state, in which it is usuaUy firmer than in their pre-
vious stages of existence. In this respect, however it
varies much in the different Orders, and evenm the dif-
ferent genera of the same Order. In some Coleopterous
insects, for instance, it is very hard, and difficult to per-
forate ; while in others it is soft, flexible, and a pm easily
passes through it^ And in general, from a substance

a See above, p. 86, 110,243— „ TlHcr are eX-

» Many species of HuUr, Curcuho L., Dorj/phora Ilhg. arc eX

EXTERNAL ANATOMY OF INSECTS.

395

in hardness resembling horn or shell, it passes through
the intermediate degrees of that of leather and parch-
ment, almost to a thin membrane. Yet in all cases there
is enough of rigidity and hardness to answer the princi-
pal uses of a skeleton — to afford, namely, a sufficient
point of attachment for the muscles, and to support and
defend the interior organization; so that the play and
action of the vital and secretory systems may not be in-
terrupted or impeded.

With respect to the principles which enter into the
composition of this integument, very little seems to be
known at present; but few insects havuigbeen submitted
to a chemical analysis. The blister-beetle {Cantharis
•oesicatoria), from its importance in medicine, has, how-
ever, been more than once analysed; and though the
products have not been very precisely stated, yet we find
amongst them phosphate of lime, albumen, and some
other usual components of the substance of vertebrate
animals ^. But which of these products belong to tlie
integument, and which to its contents, cannot be ascer-
tained, without a separate process for each ; which would
not, I conceive, he very feasible. The substance, how-
ever, of the mtegument of insects, though we know not
its precise contents, which probably vary in different ge-
nera, &c., appears not to be exactly of the nature of any
of those substances after which it has usually been deno-

tremely hard, while Cantharis GeofFr., Meloe F., and Telephones
GeofFr., are very soft.

» Thenard Traite de Chimie Elementaire, iii. 637, n, 2005. The
other products he mentions are- a green oiJ, a yellow substance, a
black ditto, acetic acid, uric acid, phosphate of magnesia. The vesi-
cant matter consists of little micaceous lamince soluble in boiling al-
cohol and oU, but insoluble hi water.

396 EXTERNAL ANATOMY OF INSECTS.

mmated : it is not properly analogous either to real horn,
sheik skin, or leather, &c. This seems to result from the
following circumstance :— Most of the excretions of ver-
tebrate animals, as horn, skin (at least when tanned),
feathers, wool, hair, &c. when exposed to the action of
lire liquify, more or less, before they incinerate; emitting
at the same time a peculiar and disagreeable scent : but
upon applying this test to the parts of insects of the dif-
ferent Orders, I found, in every instance, that incinera-
tion took place without liquefaction, and was unaccom-
panied by that peculiar scent which distinguishes the
others. Even the claws, which to the eye appear, as to
their substance, exactly hke those of Mammalia, birds,
&c. burn without melting, and retain their form after
red heat. That the insect integument is not calcareous
like that of the Crustacea, and the shells of Molluscce,
you may easily satisfy yourself, by immersing them in an
acid test. I made this experiment upon portions of in-
sects of several of the Orders, in an equal mixture of mu-
riatic acid and water, and the result was, not only that
all hexapods, but octopods, Arachnida, and even Scolo-
pendridcs, upon immersion only emitted a few air-bub-
bles; while, when the other myriapods, Polydesmics, lu-
lus, Glomeris, &c. and the OniscidcE, were immersed, a
violent effervescence took place; proving the different
nature of their substance. It is remarkable that the two
great branches of the Mijriapods, the Scolopendrida and
lulida {Chilopoda and Chilognatha Latr.), should in
this respect be so differently circumstanced— the latter
having a calcareous integument, and the former not.—
A further difference distinguishes these two tribes : old
specimens of the luUdcc usually lose their colour and turn

EXTERNAL ANATOMY OF INSECTS. 397

white, like Ojiiscidce ; while those of the Scoloj)e?idndce
retain it.

ii. Thefonn of msects is so variable, that it can be
reduced to no other general rules— than that, for the
most part^ the length exceeds the breadth, and the
breadth the depth, and that the upper surface is usually
convex. But to these rules there are numerous excep-
tions. Thus many Tetyrce F. {Scutellera Latr.), a kind
of bug, are as broad as they are long''; in the genus
Gonyleptes K. ^ amongst the Aptei^a^ and Epeira ccmcri-

formis, a crab-shaped spider, the breadth exceeds the
length; in Cynips, and several other Hymenoptera, in
Aa-ida K. ^ {Locusta F.), and other Orthopterous in-
sects, the depth exceeds the breadth; and in that singu-
lar beetle, Ewychora; the cockroach {Blatta); &c. the
upper surface is flat.

iii. The sculpture of the integument of insects is often
very remarkable; but as t^is will call for attention here-
after, I shall only here ^observe in general, that ornament
and variety seem not to be the sole object of those eleva-
tio^s'lind depressions which form so prominent a feature
of many of the animals in question; for by means of these,
many important purposes, that at fu-st sight do not strike
the observer, may be served : such as giving firfnness
to the crust in those places where it is most wanted; di-

Cqquebert Illustr. Icon. ii. t, xviii./. 14, 15. \
^ Linn. Trans, xii. t. xKii.f. 16.

<^ This name I would give to Loctata F., reserving, with Dr. Lea^h
the latter name to the true locicst {Gnjllus F.). The name Conoce-
phalus, by which LocustaV. has been distinguished, is better restricted
to those with a conical head.

398

EXTERNAL ANATOMY OF INSECTS.

minishing its powers of resistance in others, so that it
may yield somewhat to the action of the muscles ; in-
creasing or deducting from the weight of the body, so as
to produce a proper equipoise during its motions, whe-
ther on the earth, in the air, or in the water. The de-
pressions of the outer surface of the crust, in many in-
stances, produce an elevation of it in the interior, and
so afford a useful point of attachment to certain muscles.
This observation seems more especially applicable to
those excavations that are common to particular tiibes
or genera: thus the dorsal longitudinal channel to be
met with on the prothorax of most of the Carabi of Linne
on the inside of the crust have a corresponding ridge.
In Locusta Dux, also, (a Brazil locust,) the same part
has/owr transverse channels, corresponding with whicli
on the inside are as many septa, or ridges, to which mus-
cles are attached; and those larger impressed puncta
denominated pimcta ordinaria, which distinguish the
same part in Geotrupes and many of the Scarabaida,
within are elevated, so as to form a kind of ginglymous
articulation with the base of the anterior coxae. The
other impressed puncta so often to be seen on the diffe-
rent parts of various insects, which sometimes so intirely
cover the surface that scarcely any interval is discover-
able between them, though in many ca^s they appear to
be mere impressions that attenuate but do not perforate
the crust— yet in others, perhaps equally or more nu-
merous, they are real^or6's, which pass through the in-
tegument. If, for instance, you take the thoracic shield "
of* the cockchafer [Melolontha vulgaris), and after re-
moving the muscle &c., hold it against the light, with
the inner side towards the eye, you will see the light

EXTERNAL ANATOMY OF INSECTS.

B99

through every puncture : or take the elytra of Geotrupes
stercorariuSi or any common beetle in which these or-
gans have punctate striae, and examine them under a
lens on the inside, and you will see distinctly that the
punctures pass through the elytrum, and the membrane
that lines it ^. It is not improbable that in the case last
mentioned these pores may be of use, as the spiracles are
usually closely covered by the elytra, for the better trans-
mission of the au' to those respiratory organs. Whe-
ther the pores in the other parts of the body are for
transpiration, is more than I shall venture to affirm ; but
as insects sometimes perspire, at least this has been ascer-
tained with respect to the hive-bee this must be by the
means of some pores.

iv. Tlie integument of insects is often clothed, eitlier
partially or generally, with pubescence, or hairs of vari-
ous kinds — a circumstance which seems to have more
than one object. In Parnus, Heterocems, Gerris, Argy-
roneta aquatica, and some other aquatic insects, the end
in view seems to be to keep the water from wetting the
crust ; and in this case the covering of hairs is dense,
silliy, and decumbent. Another object is preventing
fiiction from being injurious: tlius humble-bees, that
from their mode of nidification <=, are usually more par-
ticularly exposed to it, are well clothed with hair; and
in those articulations of insects where much friction takes
place, we may often observe a dense fringe or coating of
the same substance. This you may see in the common

\ ■

» Plate XXVIII. Fig. ], 2.

^ Huber Nouv. Ohs. ii. 317. ' Vol. I, p. 502—.

400 EXTERNAL ANATOMY OF INSECTS.

Stag-beetle {Lucdnus Cerms), where the thorax receives
the head; and very remarkably at the same point in the
Hercules-beetle {Dynastes Hercules MacLeay) : but be-
sides these uses, there is probably one more universal,
which will apply as well to those thinly scattered bristles
and hairs, here and there one, to be noticed in many
insects: but concerning this I can only throw out a con-
jecture, as I do not recollect ever to have seen any ex-
perunents with regard to this use of animal hairs. But
may they not act as conductors, either to introduce
some invisible fluid into the body in a positive state, or
to convey it out, when received by other means, in a ne-
gative state ? Every one knows that the fur of a cat has
electric properties, and there may be an important gene-
ral use of this kind attached to the fur and hairs of ani-
mals ^ But, as I said, I give this as a mere conjecture;
and only wish it may excite your attention to the subject,
and put in exercise your natural tact for experiment.

M. Cuvier regards the hairs of msects as merely a
continuation of the epidermis, with which they fall when
the animal changes its skin^ but this will apply only to
tlie hairs of larvse: for the hairs of perfect msects m
many cases are implanted in a pore, and pass through
epidermis or crust to the membrane that Imes it, m which
they terminate.

V We are now to consider the composUio7i of the in-
tegument; under which term I would mclude the diffe-
rent layers of which it consists, and its articulation.

» Hair, in the Holy Scriptures, is used as the symbol of strength
or power. Judges xvi. 17—. 1 Cor. xi. 10.
^ Anat. Compar. ii. (524.

EXTERNAL ANATOMY OF INSECTS. 401

1. With respect to the J^rst of these circumstances, the
%m of which the integument consists, it seems to ex-
hibit some, although not an exact, analogy with the skm,
rather than the skeleton, of the vertebrate animals ^ In
these last, the skin is stated to consist offow- layers.
Of these the exterior one is'the epidermis, or scarf-skin:
under this is the rete mucosum, or mucous tissue, which
gives its colour to the skin; next follows the papillarT/
tissue formed by the extremities of the nerves, and in
which the sense oUo^lch principaUy resides; the last and
innermost layer is the shin proper, or leather, called Der-
mis, Derma, or Corium Two of these layei's M. Cu-
vier assigns to insects. They have, he observes, in every
state, a true epidermis^; and m their state of larva he
finds that the infinite variety of colours that so adorn
many of them is produced by a mucous substance ob-
servable between the epidermis and the muscles": this
seems analogous to the rete mucomm. To this, dried
and mixed with their horny substance, he attributes also
the colours of the perfect insect : « for," says he, « when
the Lepidoptera are m the chrysalis, the litde coloured
scales which are to ornament their wings, are then in a
state of mucosity sknilar to that which is found under the
skin of the caterpillar. Tlie colours of the Arachnida,"
he goes on, « are also due to this mucosity: it is disco-
verable under the skin, and has the appearance of mi-
nute glandular points of which the shades vary consider-
ably. But in the Coleoptera, and many other 0)-ders, the

» Anat.Cowpar.\.\\^. u /^.v/. ii. 540.

VOL. nr. 2d

402 EXTERNAL ANATOMY OF INSECTS.

colours of the skin are mixed in its horny tissue, nearly as
those of the Testacea are in their calcareous shells In
the perfect insects, therefore, in most cases, we may con-
sider the epidermis and rete mucosum as together form-
ing the exterior and coloured integument of insects—
that part which in the table, since it is not properly an
epidermis, I have distinguished by the name of Exo-
derma.

The learned author just quoted has observed nothing
under the skin of white-blooded animals that he regards as
analogous to nervous papilla \ In some parts of insects,
as in the lamellae of the antenna of the Petalocera, and the
extremities of the joints, especiaUy the last, of many palpi,
there is however an appearance of them ; and it seems
reasonable to suppose that where the sense of touch re-
sides, there must, even in msects, be something of ^pa-
pillaiy tissue.

With regard to the innermost integument of the ver-
tebrate animals,-the leather, or real skin,-this learned
comparative anatomist finds nothing analogous to it m
the integuments of insects ; but as he does not notice it,
he appears to have overlooked the substance that lines
the outer crust, or exoderma, in the Coleoptera and most
other orders. This is not always easily detected; but it
may generally be discovered by breaking, or rather tear-
ing (not cutting), alter having cleared away the muscles,
any part of the body of an insect. It is always very vi-
sible on the under side of elytra \ but is not discoverable

a Aunt. Compar. ii. 553. " Ibid. 557. Ibid. 560.

•i Platk XXVIIl. Vic. 2. a'".

EXTERNAL ANATOMY OV INSECTS. 4-03

in tegmina. It appears to consist, in many cases, of se-
veral layers of a whitish membrane, and generally breaks
into fibres. In some elytra of the larger Dynastidee,
towards the sides the exterior layer is separated from the
rest by a kind of cellular substance. The fibrous struc-
ture of this inner skin (which I call tlie Esoderma) seems
to give it some affinity to the skin of vertebrate animals ^
In many parts of die body, however, it appears to be
merely a thin pellicle. A medical iriend, to whom I
showed specimens of it, thinks it a kind of cellular mem-
brane.

2. A few words are next necessary with regard to tlie
articulation of the integument, or the mode by which the
several pieces of which it and its members consist, are
united to each other. In some, as in several of the parts

of the head, the occiput, vertex, temples, cheeks, &c.

the line of distinction is merely imaginary ; in others an
impressed line separates a part from its neighbours, as is
the case with the 7iose in Vespa, &c. the head in the
Arachnida. But m the majority of instances the parts
are separated by a suture, or fbrm a real joint. The
kinds of articulation observed by anatomists in vertebrate
animals do not all occur in insects, and they seem to
have some peculiar to themselves. Thus, for instance,
they have no proper suture; for diough they exhibit the
appearance both of the harmonic and squamose [ecait-
leuse Cuv.) sutures ^ yet these parts being all limited by

" Aiiat. Comjiar. ii. 557.

" A harmonic suture is when the margins of two flat bones simply
touch each other, without any intermediate substance; and a ^r/L.
mose, when the thin margin of one covers that of the other Anal
Compar. 1. 124. \^ith regard to the flat portions of tlie integument of

2 D 2

4,04. EXTERNAL ANATOMY OF INSECTS.

the esoderma, or skui, above noticed as lining the inte-
o-ument, and all admitting a degree of motion more or
fess intense, rather afford examples, as the case may be,
of other kinds of articulation Again, they have no
proper Enarthrosis, or ball and socket; though the an-
terior coxae of the Capricorn-beetles {Ceramhyx L.) ap-
proach very near to this kind of articulation, as wUl be
shown more fully in another place. The inosculatmg
segments or rings, which distinguish the abdomen, and
sometimes other parts of insects, are an example of a
kind of articulation not to be met with in the Vertehrata.
The o-inglymous articulation, in which the prommences
of the ends of two joints are mutually received by then-
cavities, and which admits only of flexion and extension,
often prevails in the limbs, &c. of insects; but in many
cases the joints are merely suspended to each other by a
h^ament or membrane; and, in fact, the integument oi
insects, with regard to its articulation, even where the
Joints ginglymate, may be said in general to consist of
pieces connected by the internal ligament, membrane, or
skin that lines it; for even in the legs, where the gmgly-
mous articulation is sometimes very remarkable and
complex, as will be shown to you hereafter, the jomts
are also connected by this substance, as you may see it
you examine the legs of any Coleopterous insect.

insects, they have some motion; whereas a suture is an articulation
^^?SrSof;:.ean, of ^^ZT^

EXTERNAL ANATOMY OF INSECTS. 405

The number of articulations or pieces that form the
integument and its members in these animals, varies
greatly in different tribes, genera, &c. Thus, in the com-
mon louse {Pediculus humanus) they scarcely reach fifty, .
while in some cockroaches {Blaita) they amount to more
than eight times that number.

Having premised these observations on the external
anatomy of the body in general, in the remainder of the
present letter I shall confine myself to the consideration
of the head and its parts.

I. The Head of insects, as the principal seat of the
organs of sensation, must be regarded in them, as well
as in the vertebrate animals, as the governing part of the
body. It may be considered w^ith respect to its stih-
stance,Jigure, composiiion, superfcies, proportion^ direc-
tion^ artiadation with the tnink^ motions—and more par-
ticularly as to its parts and appendages.

i. With regard .to its substance— the licad may be said
in general to be tlie hardest part of the crust: and it is
so for very good reasons. In the first place, as it has to
make way for the rest of the body when the animal moves,
it is thereby best fitted to overcome such resistance as
may be opposed by the medium through which it has ta
pass; in the next, as it bears the organs of mandu cation,
it was requisite that it should be sufficiently firm and so--
lid to support their action, which is often upon very hard
substances; and besides this, as no motion of its parts
i7rter se, as in the case of the trunk, is requisite to fa-
cilitate the play of its organs, a thin integument was
not wanted.

406 EXTERNAL ANATOMY OF INSECTS.

ii. The most general law relative to ihejigure or shape
of the head seems to be, that it should approach to that of
an equilateral triangle, with its angles rounded, and the
vertex being the mouth ; and that the vertical diameter
should be less than the horizontal, whether longitudinal
or transverse. But the infractions of this law are nume-
j-ous and various. Thus, in some insects an isosceles tri-
angle is represented by the head, the length being greater
than the breadth ; in others, instead of being flat it is
compressed, so diat the horizontal diameter is less than '
the vertical; in others, again, it is orbicular, or round and
depressed ; in others nearly spherical : occasionally it is
rather cylindrical. In many instances it is very long ;
in others the width exceeds the length. Though often
narrowest before, in some cases the reverse takes place.
Its anterior end is often attenuated into a long or short
snout or rostrum, and its posterior into a long or short
neck. Its contour, though usually regular, is sometimes
either cut into lobes, or scooped out into sinuosities.
But to enumerate minutely all the variations of form
which take place in the head of insects would be end-
less; I shall therefore proceed to the next particular.

iii. The composition of the head- is very simple; for,
exclusive of its organs, it consists only of a smgle piece
or box, without suture or segment, witii an aperture at
the end below to receive the instruments of manducation,
others for the eyes and stemmata when present, and also
for the antennae. In the Arachnida, &c., in which the
head is not separated from the thorax, it is merely a
plate, the under-side or cavity of which is occupied a.d
filled by '^^^"^'^ instruments.

EXTEUNAL ANATOMY OF INSECTS.

407

iv. With regard to its superficies, the head of insects
is generally more or less uneven, though in some cases it
presents no inequalities. In many of the Lameilicorn
tribes, and a few other individuals, in one sex at least,
as has been before observed*, it is armed with long
horns, or prominent tubercles ; it is often covered with
numerous puncta, or pores ; and some of its parts, as the
nose, after-nose, &c. in particular groups, marked out
by an impressed line ^. In many Hymenoptera, Diptera,
&c. its upper surface is convex, and the lower concave ;
in others both surfaces are convex.

V. It is the most general rule, as to its proportion, that
it shall be smaller than either trunk or abdomen ; but in
some instances, as in the S. American ant, Atta megace-
phala, it is much larger than either.

vi. By the directioti of the head, I mean its inclina-
tion with respect to the prothorax. The most natural
direction, or that which obtains most generally, is for it
to form an angle more or less obtuse with the part just
mentioned. This seems to obtain particularly in Coleo-
ptera but in some, as Mylahris, it is inflexed, forming
an acute angle with it. In the Heteropterous Hemiptera
{Cimex L. &c.) it is generally in the same line with the
body, or horizontal ; and in many Diptera it is vertical.

vii. We now come to a circumstance which will de-

» See above, p. 309—.
In the horiwl and other wasps, this line on the inside of the
head furnishes a foundation for a septum, which in the sides of the
nose is very high, and connects also with the hind part of the head.

408

EXTERNAL ANATOMY OF INSECTS.

tain US longer, namely, its articulation with the trunk,
or rathe: with its anterior segment, the protJwrax. —
M. Cuvier makes too principal kinds of articulation of
the head upon the prothorax, in one of which the points
of contact are solid, and the movement subordinate to
the configuration of the parts ; in the other, the articula-
tion is ligamentous, the head and the thorax being united
and kept together by membranes.

1. The Jirst of these kinds of articulation — that by the
contact of sohd parts — takes place, he says, \nfour dif-
ferent ways. " In the most common conformation, in
the part that corresponds to the neck, the head beai's
one or two smooth tubercles, which receive correspond-
ing cavities of the anterior part of the prothorax observ-
able in the Lamellicorn and Capricorn beetles. In this
case the head can move backwards, and the mouth for-
wards and downwards. The second mode of solid arti-
culation takes place when the posterior part of the head
is rounded, and turns upon its axis in a corresponding
cavity of the anterior part of the prothorax ; as may be
seen in Curculio, Reduvius, &c. The axis of motion is
then at the centre of articulation, and the mouth of the
insect moves equally backwards and forwards, upwards
and downwards, to right and left. — The t/iird sort of ar-
ticulation, by solid surfaces, takes place when the head,
truncated posteriorly, and presenting a flat surface, is
articulated, sometimes upon a tubercle of the thorax,
and sometimes upon another flat and corresponding sur-
face, as in almost all the Hymcnoptera and the majority
of the Diptera. The disposition of the fourth kind of
articulation allows the head only the movement of the
angular hinge {Ic md mouvemcnl dc charniere angidaire).

EXTERNAL ANATOMY OF INSECTS. 409

The only examples at present known are in some species
of AUclahis F. The head of these insects terminates
behind in a round tubercle, received in a corresponding
cavity of the thorax : the lower margin of this cavity has
a notch, and permits the movement of the head only in
one direction

2. The second kind of articulation, tlie ligamentous,
he affirms takes place only in orthopta-ous and some
neuropteroits insects : " The head in this kind of articula-
tion is only impeded in its movements towards the back,
because it is stopped there by the advance of the pro-
thorax ; but below it is quite free. The membranes or
ligaments extend from die circuit of the occipital cavity
to that of the anterior part of the prothorax, which gives
a great extent to the movement

When I consider the well-deserved celebrity of the
great author whose words I have here quoted, and the
great and useful light that the genius and learning which
conducted his patient labours and researches have thrown
over every department of comparative anatomy, — a sci-
ence he may be almost said to have founded, — I feel the
most intire reluctance to differ in any thing from an au-
thority so justly venerable to all lovers of that interesting
study. But, however great my diffidence and hesitation
to express an opinion at all opposed to his, the interests
of truth and science require that I should state those
particulars in which my own observations, made upon a
careful examination of various insects of every Order,
have led to results in some respects diiferent from the

' Anal. Compar. i. 445 — .

•> Ibid. 41/.

410 EXTERNAL ANATOMY OF INSECTS.

above. " Aliquando bonus dormitat Homerus and
if the Genius of Comparative Anatomy ever nodded, it
sometimes happened when he was examining the struc-
ture of insects. An instance of this with regard to the
mouth of the bee has been noticed by Mr. Savigny";
and indeed it is not wonderful that in so extensive an
undertaking, in which the number of examples to be ex-
amined upon every branch of his subject must be im-
mense, that he did not always scrutinize minutely those
that seemed less important. Every writer on every de-
partment of Natural History, especially where the ob-
jects of research, as in the msect world, are so infinite m
number, will be liable to such mistakes; but these will
meet with due allowance from every candid mind—

" Hanc veniam damus, petiinusque vicissim :"
and I shall express my trust that you will overlook any
errors of mine; and doubtless I shall not be free from
them —

« . — Quas aut inciu-ia fudit,

Aut humana parum cavit natura "

The two kinds of articulation of the head which our
learned author has stated as the principal ones, will, I
think, be found upon examination not so widely distant
as his expressions seem to indicate; for in fact in all m-
sects, as well as the Orthoptera, this part is suspended by
a membrane or ligament which unites the margins of the
occipital cavity with those of the anterior one of the pro-
thorax: thus forming all round some protection to the

a Mem. SUV les Anhn. sans Verlcbr. I. i. 1 1- Conip. Anaf. Com-
par. iii. 314 — .

EXTERNAL ANATOMY OF INSECTS.

411

organs that are transmitted from the head through the
latter part to the rest of the bod3\ Though the head in
most Orthoptcra is not partly received into the cavity
of the prothorax, as is the case in the Order Coleoptera,
but is rather suspended to it, yet in some instances, for
example in the mole-cricket {Gryllotalpa vulgaris), it is
paitially inserted.

Again : when, in his ^rst mode of articulation by con-
tact of solid parts, he sjieaks of one or two smooth tu-
bercles of the neck, with their corresponding cavities in
the prothorax, as forming the most common conforma-
tion, you would expect to find examples of this in very
)nany insects ; yet upon a close examination, unless in
Orvctes nasicornis and perhaps in others of the Dij-
nastid(S MacLeay, you would scarcely meet with any
thing that could be called a tubercle and its correspond-
ing cavity in the neck or prothorax of any Lamellicorn
or Capricorn beetle that you might chance to examine.
You would find, indeed, that the occiput was usually
smooth and very slippery, as if lubricated ; that in its
margin were one or two notches {Myoglyphides), with
muscles attached to them ; that in the former of these
tribes, the Larnellicurns, it projected on each side so as to
form a more or less prominent angle ; and that the throat
{jugtilum) was very convex, and lodged in a cavity of the
lower margin of the prothorax : but further appearances
of tubercles &c. you would in vain look for even in tliis

It is probable that M. Cuvier took his idea of this first kind of
articulation, by contact of solid parts, from tiiis individual insect;
bince, besides its very prominent throat, there is on each side of the
lower part of the occiput a small elevation, or approach to a tu-
iiercle.

4)12 EXTERNAL ANATOMY OF INSECTS.

tribe ; and in the Capricorns you would find that the ge-
neral conformation in this respect belonged to our learned
author's secdnd mode of solid articulation, resembling
that of the majority of the weevils {Curcidio L.), in which
the head has no projecting angles or tubercles, or other
elevation, but is received usually into the circular cavity
of the prothorax.

His third mode of this articulation, that of the Hymeno-
ptera and Diptera, is so peculiar, that it ought to be con-
sidered as a primary kind ; since in this the head moves
iipon the prothorax as upon a pivot, and has a kind of

versatile motion.

With regard to hxs fourth mode, which from his de-
scription appears to be that o^ Apoderus Oliv., he allows
motion to the head only in one direction, observing that
the lower margin of the prothoracic cavity has a notch.
But M. Latreille calls the articulation of the head in this
genus an Enarthrosis % which admits motion m every di-
rection ; and if you examine the common species {A. Co-
ryli), you will find that the prothorax has a sinus taken
out of its upper margin, as well as out of its lower one—
which at any rate will allow a motion upwards.

I merely mention these little inaccuracies, with due
diffidence, as some apology for giving you a different and
at least a more popular and general view of this part of
my subject, which I shall now proceed to state to you.
It seems to me most convenient for the Entomologist, and
most consonant to nature, to divide insects, with respect
to the articulation of the head with the trunk, into three
primary sections, each admitting one or more subdivi-
sions.

« Gen. da Crudac. el Ins. ii. 246. Rcgnc Anim. m. 325.

EXTERNAL ANATOMY OF INSECTS.

413

1. The Jirst consists of those whose head inosculates
more or less in the anterior cavity of the chest; and
whose articulation, therefore, seems to partake in a greater
or less degree of the ball and socket {Ejiarthrosis). The
liead, however, is often capable of being protruded from
this cavity. If you take into your hand any common Har-
palus that you may find under a stone, you will see, if
pressed, that it can shoot forth its head, so as to be en-
tirely disengaged from the prothorax : a neck of ligament
intervening between them ^ : of course this power of pro-
truding the head enables the animal to disengage it at its
will from the restriction imposed upon its motions by the
surrounding margin of the prothoracic cavity. To this
section belong all the Coleoptera, the Heteropterous Hr-
miptera (CimexL,., &c.), and some of the Neuropiera (lia-
phidia, Semblis, &c.). — It may be further divided into two
subsections — those, namely, whose head inosculates in
the prothorax by means of a neck : as for instance La-
treille's Trachelides, Apodcnis^ and the Staphjlinidce,
amongst the beetles ; the Reduviadce amongst the Hete-
ropterous insects, and Raphidia in the Neuroptera and
those whose head inosculates in the prothorax without
the mtervention of a neck ; as, the Petalocera, the aqua-
tic beetles {Dytiscus, Hydrophilus^ &c.), and most of the
genus Curculio L. in the first of these oi'ders, the great
body of the Cimicidcc in the second, and Semblis, Cory-
dalis, &c. in the third.

2. The second section consists of those insects whose
head does not inosculate in the chest, but is merely sus-

» This was written directly after the experiment recommended in
the text had been tried, with the result there stated.

4'14< EXTERNAL ANATOMY OF INSECTS.

pended to it by ligament or membrane. To this belong-
most of the tribes of the Orthoptera Order, with the ex-
ception of the Mcmtidce, the Dermajytera, the Homo-
jpterous HemijJtera, and such of the Apt era as have the
head distinct from the prothorax.— This section admits
of a triple subdivision : those, namely, whose head is
wholly/ covered by the shield of the prothorax, as in
Blatta L.; those whose head is partljj covered by it, as
Gryllotalpa, and other Gryllina; and those whose head
is quite free, not being at all impeded in its motion by
the prothorax, as the Dermaptera, Nirmus, Fedicu-
lus, &c.

3. The third section consists of those whose head is
truncated posteriorly, and flat or concave, with a very
small occipital aperture, and is attached to a neck of the
prothorax upon which it turns, or is merely suspended
to that part. This includes the Lepidoptei-a, Hijmeno^
ptera, Diptera, the Libdhdina, &c. m the Neuroptera,
and the Ma^itidce in the Orthoptera. Three subsections
at least, if not more, present themselves in this section:
the first is, of those whose head is united to the protho-
rax, without the latter forming any nec/c. To this belong
the Lepidoptera, Trichoptera ? The second is of those
the upper side of whose thoracic neck is ligamentous;
and here you may range most of the Hijmenoptera. The
third is of those in whom it is a continuation of the ordi-
nary integument. In this subsection the Diptera, Lihel-
lulina and Mantid<JO will find their place. In this last
section the head appears to turn upon the thorax as upon
a pivot.

Before I finish what I have to say on the articulation
of the head, I must direct your attention to the analo-

EXTERNAL ANATOMY OF INSECTS.

4-15

gie^ that hold in this respect between the different tribes.
Thus the Coleojytera are analogous to the Heterojjterotis
Hemiptera; the Orthoptera^ with the exception of the
Mcmtida, to the Homoptcrous Hemiptera ; the Mantidcc
to the Libellvlina; the Lepidoptera to the Tric1ioptei-a ;
the Hymenoptei-a to the Diptera, with a slight variation,
and probably others might be traced. *

viii. A word or two upon the motions of which the
head of^psects is capable. M. Cuvier, in the extracts
lately laid before you, speaks of different powers of move -
ment as the result of different configurations of the parts
of the head. This probably is correct with regard to
many cases ; but a gi-eat deal will depend upon the power
the insect has of protruding its head and disengaging
its base from the restriction of the prothorax ; for where,
like the Harpali, Staphylini^ &c. it is able to do this, it
can probably move its head in every du-ection. It is
only where the ligaments are less elastic, or allov/ of lit-
tle tension, that its movements are confined ; and few
living insects have been sufficiendy examined to ascer-
tain how far this takes place. In those cases belonffinff
to the third section of articulations, in which the head
moves icpon the thorax as upon a pivot, as is the case
with Hymenoptera and Diptera, the movement is nearly
versatile. I have seen a fly turn its bead' completely
round, so that the mouth became supine and the vertex
prone; and from the form and fixing of the head, it
should seem that those of the Mantidce were endued
with the same faculty.

ix. The 2^arts and appendages of the head are now in

416 EXTERNAL ANATOMY OF INSECTS.

the last place to be considered. I shall beghi with the
Mouth, or rather the orifice in which the trophi or organs
of manducation are inserted. In some insects, as was be-
fore observed, they occupy all the under-side of the head,
as in the Arachnida, Myriapoda, &c.; but in the great
majority they fill an orifice in its anterior part, which in
some instances, as in Lampyris, the Lepidoptera, Ci-
mex L., Truxalis, appears to be nearly under the head ;
but in general it terminates that part, though it extends
further below than above. In Chermes, a Homopterous
genus, the promuscisis stated to be in the Antepectus, and
consequently the mouth; but, as I shaU endeavour to prove
to you hereafter, this is a fallacy. In the males of the
species of Coccus there is no mouth at all. In diat of the
elm (C. Vlmi) in lieu there are ten little shining points,
arranged two before and two behind in a line, and three
on each side in a triangle ^ It is to be observed that the
orifice of which I am speaking is usually much smaller
m those insects which take their food by suction, the
Heviiptera, Lepidoptera, Diptera, &c., than in the mas-
ticating tribes. With regard to the real mouth, or that
through which the food enters, I have nothing at present
to obs^'erve, except that it lies between the upper-lip and
tongue, is sometimes covered by a valve, as in Apis,
Vespa\ &c., and is different in the masticators and
suckers.

I shall next offer a few observations seriatim, as they
stand in the Table, upon the organs of manducation ;
which, to avoid circumlocution, instead of Instrmncnta

» Reaum. iv. 40. Latreille Fourmn, 328-. " Plate VII. F.c 2. k".

Synoptical Table of the NomencJatitre of the Parts of the external Crust of Insects

Os < Tropin.

Facies a .

Subfacies e

Collum i

^Cephalophragnia

'MaiiitruncQS a .

Nasus a . . . ,
Postnasm b
Frons c
Vertex d
Occiput e
• GcncE f
Tcinporn g

OciJi h

Stemimia i

AntenncB k .,
Lora 1

Nucha n. . . .
Giila o

(Prothorax a
I

Labrum a' j. \ Appendimda

. , . , , ! ( Mentwn a"

Labium b | ^ p^^- i^iw/w b"

j C ProsUieca c" C Incisores a'"

Maadibulae c' X>(?Mfes ■] Laniarii b'"

I ( Mola d" ( Molares c'"

{Cardo e"
Stipes f" C Superior d'"

Lo&i g" ] Inferior e'"

Palpi Maxillares h" ( Ungues f"
Lingua e' * { Paraglossa: i"

Pl'^y"^^; iHypo^^^^^^
. ^ RUinarium g'

{ Canthus h'
TTorulus i' I

J Scapus k' I *t BiMusl"

i Pedicellus l|

l,Clavola m'l ^ CapUuhm i

. Myoglyphidfes n'

{^Antcpecttis b .

'Ora a' I

Patagia b'

Umbones
_ Phragina

' Spiraeula Antepec-

toralia c .
Prosternmn d'
Antefurca e

_ Brachia /' .

" Chivicitla
Scapvia
Humerus

j Cubitus .

L Maiuis d'

_Alitruncus c ..

Mesothorax c. ■

Medipectus d. .

Metathorax e.

Collare g
Prophragma li
Dorsolum i' ...
Scutellum /('
Fraenuni /'
Pn^'stega wi'

r Peristethium n'

1 Scapularia o'

< Mesosternum p
Medifurca ^
Pedes Intermedii ;
' Mesophragraa s
Postdorsolum t
Postscutellum u'
Postfraenum v
Pleurce iv

Pferopegee b"
Elytra c" . . .
Tcgmina d"

Hemeltftra e"

{ Coronula

\ Calcaria ,

X Palma

\ Digitus

f Hj^oderma d
I Axis b'"
< Sutura c'"
I Epipleura d'"
L Alula e'"
t Corium f"
I Membrana g"

Axes h"

Arete i'"

, ^ Velum a *
■ \ Unguia .

Metaphragma x
Mesostethiuin y
Parapleura ^

_ pQsipectus f .

Metastemum af .
Poatfiuca 6 +
Opercula c\

.Pedes Postici rff ... •

Ala supeiiores f" . .
Tegtdie ^

Spiraeula scapula-
ria h"

( Alee Inferiores i" . ■
' I Metapnystega h"
. \ Septula I"

C Spiracida Parapleu-
' ) riiica ni"
. ^ Pcet'mes li'

Neui-ae .".

Stigma vi"
Parastigma
Lobuli 7i"'

Commissura d"

Tendo

Hamuli

Pterygium

Alula

_ Halteres p'"

\ Pollex
t Palmula

Costalis b'
Ivterinedia c '
Aiialis d '
Bnsilarcs c •
Media: f-
Apicnlcs g-

Costalis h- ^ U^mxxs

Postcostalis i ■ Subcostalis a*

Jllediasiina k

Extemo-mcd'ui I •
Intemo-mcdia vi •
Analis n •
Axillaris o •
Spuria p •

Subexterno-media b*
Subinterno-media c *

Acetabula o" < PesseUa (}"'

Coxa p"
Trochanter q"

Femur r" < Gonytheca

TEpicnemis

T'Ma s"

L Tarsus t'

, Molula i'"
\ Talus d"
I Calcaria »"'
y Coronula
Planta -vd" . .

Digitus .r'" - .

LSolea y" ■

\ Calx q •
5 Allux r-
\ U'tgula s •
. I Fulvilli t •

C Arthrium d *
. \ Unguiculi e *
I Plantula/* ... ^ Pseudonychia

'Terguni A
Venter B .

Petiolus C .

Cauda D .

_Anu> E.

C SegvientaDorsaliaA
\ Pulmonaria B

I Hypochondria C
Epigastrium D'
Segmenta VeiitraliaEf
Elastcs
^Funiculus F'
. ^ Foramai G'
' Squama H'
L Nodus I'
• ^ Ccnlns
(Podex K'

Hypopygium L'
I Cidus
Oviposiior M' .•

J^ Spii-aculaDorsalia «4"

( Mucro B"
I Tympana C"
C Spiraeula Ventra-
\ lia D "

Aculeus N'.

{^Appendices C

rUnci E'
1 Valvae F"
\ Vaginula G"
l^Terebellae H"
^ Spicula
'Forceps K"

Forfex L"

Furca M"

Styli N-

Foliola a'

Flosculus P'

Cerci a"

Caudula R"

Fila 5"

MammulEB T"

_Siphonuli U"

TnuNCUS quoad Par
supina et prona si- i
mtdsnmpta

. ^ Rcfinaridum A'"

Prothorax a
Mesothorax c
Mctathorax e
Antepectus b
Medipectus d
Postpectus /
Prosternum d
Mesosternum p
^ Metasternum a
C Antefurca e
.. } Medifurca ^
I Postfurca b f

. ^ Fusi B"'

y. M. The Lotte.. in thi» Table that follow the Na.„es of the Parts, are used in the Plate, to iadicate the san.c Pa*.

EXTERNAL ANATOMY OF INSECTS. 4] 7

cibariay the name Fabricius gave them, I shall call tropin
ov feeders. It is upon these parts, you are aware, that
the system of the celebrated Entomologist just mentioned
is founded; and could they always, or even for the most
part, be inspected with ease, diey would no doubt afford
characters as various and discriminative as those of the
vertebrate animals. Differences in these parts indicate
a difference in the mode in which the animal takes its
food, and often in the kind of food, and sometimes in its
general economy and habits,— circumstances which are
powerful and weighty in supporting the claim of any set
of animals to be considered as forming a natural genus
or group. Trifling variations, however, of these parts,
unless supported by other characters and qualities, ought
not to have much stress laid upon them, since, if we In-
sist upon these, in some tribes almost every species might
be made a genus.

With respect to their tropin in general, insects of late
liave been divided into two great tribes % masticators ^nd
Slickers; thejrst including those that are furnished with
mstruments to separate and masticate their food; namely,
an upper- and under-lip (lab-um and labium), upper- and
under-jaws {ma?idibulce and rnaxillce),. labial and maxil-
lary palpi, and a tongue (lingua): and the seco,id those
m which these parts are replaced by an articulate or ex-
articulate machine, consisting of several parts and pieces
analogous to the above, which pierce the food of the ani-
mal, and form a tube by which it such its juices. If,
however, the mode in which insects take their food be

- ClairviUe (Ent. HelveL i. 44) appears to have been the first who
classed insects according to their mode of taking their food.
VOL. jir. 2 E

4-18 EXTERNAL ANATOMY OF INSECTS.

Strictly considered, it will be found that in this view they
ought rather to be regarded as forming three tribes; for
the great majority of the Hymenoptera order, and per-
haps some others, though furnished with mandibles and
maxillae, never use them for mastication, but really lap
their food with their tongue: these, therefore, might be
denominated lajij^ers.

When a mouth is furnished with the sen^en ordinary
organs used in taking the food and preparmg it for de-
glutition-I mean the upper-lip and the two upper-jaws ;
the under-lip and the two under-jaws, including the la-
bial and maxillary palpi; and the tongue-I denommate
it 2. perfect mouth but when it is deficient m any of these
oro-ans, or they exist merely as rudiments, or when then-
place is supplied by others, (which, though they may be
analogous parts, have little or no connection mth them
in their use or structure,) I denominate it an vnperfect
mouth. This last I would further distinguish, accordmg
to the nature of its trophi, by other and more distmctive
terms, as I shall presently explain to you.

1. Lahrum\-l shall first consider the organs pre-
sent in ^perfect mouth beginning with theupper-Up {la-
brum). This part, which Fabricius sometimes confound-
ed with the nose, miscalling it clypcus, is usuaUy a move-
able'' piece, attached by its base to the anterior margin
of the part last named, and covering the mouth, anc.
sometimes the mandibles, from above. Iir msects m
their last state it is usually of a horny or shelly suhstance;
yet in some cases, as in Copris and Cetonia, beetles that

: the law seei. to ^on. the under-

side of the nose, and to be connate with it.

EXTERNAL ANATOMY OF INSECTS. 41 9

imbibe juices, it is membranous. In form and shape it
varies greatly, being sometimes nearly square, at others
almost round; in some insects representing a parallelo-
gram, in others a triangle, and in many it is oblong. In
some instances it is long and narrow, but more generally
short and wide. It is often large, but occasionally veiy
minute. In the majority it has an intire margin, but it is
not seldom emarginate or bilobed, or even dentate. Its
surface is commonly even, but it is sometimes uneven,
sometimes flat, at others convex, and in a few species
armed with a short horn or tubercle As to its ^pubescence,
it is often naked, but now and then fringed or clothed
with down or hairs, or sprinkled with bristles. It con-
sists in almost every instance of a single piece; but an
exception to this occurs in Halictus, a little bee, in the
females of which it is fiirnished with a slender appen-
dage •'.—The direction of the upper-lip is various. It is
rarely horizontal, or in the same line with the nose, often
vertical ; it sometimes forms an obtuse angle with the
anterior part of the head, and occasionally an acute one,
when it is more or less inflexed. The use of this part is
oi-dinarily to close the mouth from above, to assist in re-
taining the food while undergoing the process of masti-
cation ; but in many Hymenopterous insects its principal
use seems to be, to keep the trophi properly folded; and
in some cases where it is inflexed, as in the leaf-cutter
bees {Megachile Latr.), to defend its base, while the man-
dibles are employed, fi'om injury by their action «=.

^ Elxhy Mon. Ap. Angl. i. t. v. Apis * h.f. 18. b.
" Ibid. t. ii. Mcliita **. h.f. 4, 5. Plate XXVJ. Fig. 30.
' Platb XXVI. Fig. 31. Mon. Ap. Aiigl. i. t. x. Apis •» c. 2. 5
/• 13. c.

2 E 2

420 EXTERNAL ANATOMY OF INSECTS.

2..Labium\—On the under-side of the head, and op-
posed to the upper-lip, the mouth is closed by another
moveable organ, concerning the nomenclature and ana-
logies of which Entomologists have differed considerably.
At the first view of it, this organ seems a very com-
plex machine, since the under-jaws or maxilla are at-
tached to it on each side, and the tongue is often seen to
emerge from it above, so as to appear merely a part of it;
but as the former answer to the upper-jaws, and the lat-
ter is the analogue of the part bearing the same name m
the vertebrate animals, I shall consider these as distmct
^nd^vrmanj organs, and treat of the under-hp {lahum)
of which I am now speaking, by itself. Linne takes no
notice of this part, but his illustrious compatriot and co-
temporary, De Geer, did not so overlook it: he appears
to consider the whole apparatus, includmg the maxilla^
as the labium^; but sometimes he distingmshes the mid-
dle piece by that name <=; and the tongue, in the case of
the stag-beede, he denominates a proboscis {trompc) .
In the Hymenopera he calls this part tongue, under-hp,
and vrohoscis : but seems to prefer the last term <=. Fa-
bricius originally regarded the whole middle piece as a
labium^; but afterwards (though his definition is no ac-
curate, since he assigns the palpi to the lig2da, which he
affirms is covered by the labium-civcnmstances by no
means universal in Coleoptera) he considei. this as con-
sisting of ligrda and labium ^. Latreille at first regarded

a Plates VI. VII. and XXVI. b.
. De Geer iv. 124. t. iv./. 13 m. 4 5. ^ xx^/. 4.
cibid.iv.281-.i.xi./.7. a Ibid. 329. ^ xn./. 3.

e Ibid. ii. 775- .x.vi./. 10. b c, b . ^ ^^^^ . .

f P/iilos. Entom. 18. ^.f''"

EXTERNAL ANATOMY OF INSECTS. 421

the ligula of Fabricius as the labium, and called the la-
hium of that author the mentum^\ but afterwards he gave
the name of labium to the whole middle piece of the
lower apparatus of the mouth— calling the upper piece,
with Fabricius, the ligula, and retaining the denomina-
tion of mentum for the lower

If the circumstances of the case are duly considered,
I think you will be convinced that the term under-lip,
or labium, should be confined to that part which the
learned Dane so named. For I would ask. Which is
the part on tlie under side of the head that is the anta-
gonist, if I may so speak, of the upper-lip or labrum ?
Is it not tliat organ which, when the mouth is closed,
meets that part, and in conjunction with it shuts all in ?
Now in numerous insects, particularly the LameUicorn
beedes {Scarabaus and Lucamcs L.), this is precisely the
case. In the Predaceous beetles, indeed, {Cicindela, Ca-
rabus, Dytiscus L. &c.) the under-lip does not meet the
upper, to close the mouth and shut in the tongue; nei-
ther can the tongue be said so to do, but only, from some
circumstances connected with its manner of taking its
food, it is requisite that the last-mentioned organ should
not be retractile or covered; but its miscalled mejitum
is still the analogue of that part which helps to close the
mouth in the former tribe. Should not this, therefore,
which so often performs the office, be distinguished by the
name, of a lip ? Again, is it not rather incongruous to
consider that organ which confessedly more or less per-
forms the office of a tojigue, as a part of the lipP Though
it often wears that appearance, yet I believe, if the mat-

" Gen. Cnislac. ct Ins. i. 1 80. " N. Diet. d'Hist. Nat. iv. 246.

422 EXTERNAL ANATOMY OF INSECTS.

ter is thoroughly and patiently investigated, it will b e
found that on their upper side its roots are attached to the
interior of the upper side of the head, as well as on their
lower side to the labium; so that it may be regarded as
common to the two lips, and therefore not properly con-
sidered as an appendage of the under-hp alone.

Having assigned my reasons for preferring the name
given to the part in question by Fabricius, rather than
that of Latreille, I shall next make my observations on
the part itself. In many cases the lahium, or the middle
piece of the lower oral apparatus, appears to consist of
^wo joints: this you may see in the great water-beetle
{Hydrophilus piceus), the burying-beetles {Neq-ophorus),
the Orthopterous tribes % the Hymenoptera ^ and others.
In this case the upper or terminal piece is to be regarded
as the lahmm, and the lower or basal one (which Mr,
MacLeay calls the stipes) as the mentum or chin— at
other times, as in some LamelKcorn beetles, the only se-
paration is a transverse elevated line, or an obtuse angle
formed by the meetmg of the two parts, and very fre-
quently there is no separation at all, m which case the
whole piece, the mentum merging in it, may be denomi-
nated the lahium.

With respect to its substance, the labium in most Co-
leopterous msects is hard and horny, m Necrophorus it
is membranous, and the mentum harder; in Prionus
coriarius, our largest Capricorn-beetle, both are mem-
branous; in the bee-tribes, Apis L., the labiiim rather
resembles leather, while the menium is hard. Its surface
is often convex, sometimes plane, and sometmies even

» Plaik VI. FiG.G. b'. a"

b Plate VU. Fig. S.b'.a'.

EXTERNAL ANATOMY OF INSECTS.

4-23

concave; as for instance in Melolontha Fullo, a rare
cliafer occasionally found on the coast of Kent. In some
it is covered with excavated points ; in others it is quite
smooth. In numbers, as in the Predaceous beetles, both
labitcm and mentum are perfectly naked; in others, as in
the common cockchafer, they are hairy ; in Geniates bar-
batus Kirby, another chafer in the male insect, the la-
bium is naked, while the mentum, which forms a piece
distinct from that part, is covered with a dense rigid
beard ^. In sJiape the whole labium varies considerably,
much more than the labrum ; for in addition to most of
the forms I enumerated when I described that om-an,
which I shall not here repeat, you may meet with exam-
ples of many others. Thus, to instance in the Petalocerous
tribes {Scarabceus L.), in some, as in the Rutelidce, the
labium is urceolate, or representing in some degree the
shape of a pitcher in others it is deeply concave, and
not a little resembles a basin or a bowl-^; this form is
peculiar to the labium of Cremastocheilus Knoch, a scarce
North American beetle; in another related to this, but
of an African type {Ge7iuchus Kirby MS. Cetonia cni-
enta F.), it is a trapezoid plate, which is elevated from
the head, and hangs over the throat like a chin In the
Hymenoptera it is extremely narrow and long, and em-
braces the sides of the tongue, as well as covering it from
below; so that it wears the appearance of a kind of tube ^
Generally speaking, the length of the labium exceeds its
breadth ; but in the Predaceous beedes the reverse of

^ Kirby Z,mw. Tram. xii. t. xxlf.S.f.

^ Ibid. t.xx].f. 10. d. MacLeay Ilor. Enlonwl. i. t. iii./.26,27.

Plate XXVI. Fig. 35. d Ibid. Fig. 34.

" Plate VII. Fio. 3. b'.

424.'

EXTERNAL ANATOMY OF INSECTS.

this takes place, it being very short and wide, and usu-
ally terminating towards the tongue in three lobes or
teeth which form two sinuses varying in depth ^

The mentimi taken by itself affords no very striking
characters to which I need call your attention : I shall
only observe, that in Hymenoptera it is generally of a
triangular shape ; but before I proceed to consider the
labial palpi, it will be proper to notice the remarkable
labium of Orthopterous insects, and of the LibelluUna,
between which there is no little analogy. At first you
would imagine the terminal part of this organ m the for-
mer to be the analogue of the tongue, or ligida F. ; as it
is indeed generally regarded by modern Entomologists S
It seems, like the tongue of the Carabi L., Dytisci^ &c., to
be a distinct piece, which has below it both labium and
vientum; but when you look within the mouth, you will
find a linguiform organ ^, which evidently acts the part
of a tongue, and therefore ought to have the name; and
the piece just alluded to must either be regarded as the
termination of the lip, or as an external accompaniment
of the tongue, analogous, it may be, to the paraglosscs in
bees ^ In a specimen of Acrida viridissima {Locusta F.)
which I dissected, the tongue is as long as tlie appen-
dage of the under-lip, and by its upper surface seems
to apply closely to it. In the LibelMina a sunilar organ
is discoverable ^ which on its upper-side terminates in
t\\e pharynx, like that of one of the Harpalida before
mentioned. In the Orthoptera, therefore, I regard tlie
labium as consisting of three articulations, the upper one

" Plate XXVI. Fig. 24. b'. " Plate VII. Fig. 3. a",

c N, j)icu d'Hist. yal. xxiv. 171. " Plate VI. Fig. 6. e .
• Plate VII. Fig. 3. i". ' Plate VI. Fig. 12. e .

EXTERNAL ANATOMY OF INSECTS. 425

divided into two, three, or more lobes ^ ; the intermediate
one more directly answering to the labium of other in-
sects, and the basal one or mentum. This organ in the
Libelhilina is of a different structure : it has only two
articulations representing labium and mentum ; but the
former consists of three parallel pieces, the two exterior
ones rising higher than the intermediate one, and at their
inner angle having an acute sinus from which the palpi
emerge ; and the intermediate piece, which is longitudi-
nally channelled, lapping over the inner side of the lateral
pieces. From the angle of the covered part of these
pieces, a subulate short horizontal horn points inwards
towards the tongue, which it must keep from closing
with the labium^.

3. Palpi Labiales — The last-mentioned organs, the
labial palpi, next claim our attention ; but before I advert
particularly to them, it will be proper to premise a few
words u^onpalpi, or feelers, in general. These are usual-
ly jomted moveable organs, of a corneous or coriaceous
substance, attached by ligaments to the labium and
maxillce, and in the Crustacea even to the mandibulce.
Their joints, which are usually more or less obconical,
articulate also in each other by ligaments, with perhaps
some httle mixture of the ball and socket. Their ends,
the last joint especially, seem furnished with nervous
papillce which indicate some peculiar sense, of which they
are the instrument. What that sense is has not been
clearly ascertained, and concerning which I shall enter
more into detail in another place. Their motion seems

» Plate VI. Fig. 6. b'. b ibid. Fig. 12. b".

' Plates VI. VII. XXVI. b".

426 EXTERNAL ANATOMY OF INSECTS.

restrained, at least in some, to two directions, towards
and from the mouth. They were called palpi or feelers,
because the insect has been supposed to use them in ex-
ploring substances. There seem to be no organs in the
vertebrate animals directly analogous to thepalpi of in-
sects and Crustacea, unless, perhaps, the cirri that emerge
from the lips of some fishes, as the cod, red mullet, &c.
which Linne defines as used in exploring (i?r^/mtew/es).
Whether the vibrissa, miscalled smellers, of some quadru-
peds and birds have any reference to them, I will not
venture to affirm ; but the feline tribe evidently use their
bristles as explorers, and they are planted chiefly m the
vicinity of the mouth.

Having made these general remarks, I shall now con-
fine myself to the labial palpi. I call them labial palpi,
because that term is in general use, and because in many
cases they really do emerge from what I consider as the
labium, as m most of the chafers; but they might with
equal propriety be denominated li7igual palpi, smce they
sometimes appear to emerge from the tongue (as in the
stag-beetle {Lucanus Cervus). In some instances, as in
the^'Predaceous beetles, they seem to be common to both
labium and tongue, being attached at then- base on the
upper side to the former, and on the under side to the
latter. As to their situation : they emerge from the base
of the labium m the locusts {Locusta Leach) ^; from its
middle in Hister maximus^; from its sunwiii in Ambl^/te-
rus MacLeay-^; and from its lateral margin in Dynas-
tes MacLeay, &c. They consist of from one to four

» Plate VI. Fig. 6. b". " Hor. Entomolog. i. L If. l.g-

<^ Ibid. t.\i.f. 18. g.

EXTERNAL ANATOMY OF INSECTS.

427

joints ; which, I believe, they never exceed. They vary
in length though generally shorter than the maxillary
palpi, yet in the ferocious tiger-beetles {Cicindela L.)
they equal them in length ; and in the hive-bee and hum-
ble-bees, and many other bees, they are considerably
longer The two first joints of these palpi, however,
in these bees are different m their structure fi'om the two
last, being compressed and flat, or concave; and the two
last joints, instead of articulating with the apex of the
second, emerge fi-om it below the apex: so that these
two first joints seem rather elevators of the palpi than
really parts of them With respect to the relative pro-
portions of their joints to each other : in some cases the
first joint is the longest and thickest, the rest erowino-
gradually shorter and smaller <=; in others, the second is
the longest 'i; in others, again, the third % and sometimes
the last and often all are nearly of the same size and
lengths. They are more commonly naked, but some-
times either generally or partially haiiy. Thus in Cicin-
dela, the last joint but one is usually planted with long
snow-white bristles in a double series, while the rest of
the joints have none; and in Copris Latr. all of them are
extremely hairy. In shape they do not vary so much as
the maxillary palpi, being most fi-equentiy fihform or
subclavate, and sometimes setaceous; the last joint varies
more in shape than the rest, and is often remarkably

Erby Mon. Ap. Angl. i. t xii. neut.f. l.g.c.
" Ibid. 93. 103—. t. vi. Apis b. /. S.bc.
' -f^zf/- t. i. * a./. 3. b. <' Ibid. t. ix. Apis **. c. 2. y./ 3. h.

Clairv. Ent. Ilelvet. ii, t. xxiv /. I.e.

Plate XXVI. Fig. 24, 28. b".
= Moil. Ap. Angl. I t. ii. Mclitla **. h.f. 2. c.

4,28 EX'J'ERNAL ANATOMY Oi' INSECTS.

large, triangular, and shaped like the head of a hatchet-
and at others it resembles the moon in her first quar-
terly In the great dragon-fly, or demoiselle if you pre-
fer the gentler French name {Mshna F.) the labial palpi,
which are without any visible joints, are terminated by a
minute mucro or point^. With regard to then- direcUon
and flexure, they frequently, as in the instance just men-
tioned, turn towards each other, and lie horizontally upon
the end of the labium. Sometimes, as in the CtcmdeUdce,
they appear to point towards the tail of the insect, the last
ioint rising, and forming an angle with the rest of he
feeler In other instances they diverge laterally from the
labium, the last joint turning again towards it at a very
obtuse angle.

4 Having considered the analogues of

the 'lij,. In our little beings, I must next call your atten-
tion to the representatives of the The vertebra e
animals, you know, are mostly furnished w.dr a smgle
Tair of jaws, one above a.,d the other below, m whrch the
teeth are planted and which have a vertical motion. But
insects are furnished with two pair of jaws a pair ot
„pper-jaws and a pair of undei-jaws, have no
"ee* Wanted In them, and the motion of which is hori-
zontal.-! shall begin with an account of the uppei-jaws.
These by modem Entomologists, after Fabricius, arede-

„ rU. U the case with Of^P^^^^^^^;;^'^,,
to be so conaidercd. ""^^

EXTERNAL ANATOMY OF INSECTS. 429

nominated mandibles (matidibulcs) : a term appropriated
by Linne to the beaks of birds. The upper-jaws of in-
sects this great naturalist named maxillce — and not im-
properly, since the office of mastication is more pecu-
liarly their office than that of the under-jaws, which Fa-
bricius has distinguished by that name : as the term man-
dible, however, is generally adopted, I shall not attempt
to distxirb it.

The mandibles close the mouth on each side under the
labnm or upper-lip. They are generaUy powerful or-
gans, of a hard snbstancelxke horn; but in the LameUicorn
beetles of Mr. MacLeay's families of Scarabceidce and Ce-
toniadcB, they are soft, membranous, and unapt for masti-
cation. In Coleopterous insects they commonly articulate
with the head by means of certain apophyses or processes,
of which in many cases there are three discoverable at
the exterior base of the mandibles ; one, namely, at each
angle, and one in the middle. That on the lower side is
usually the most prominent, and wears the appearance
of the condyle of a bone : it is received by a correspond-
ing deep socket (or cotyloid cavity) of the cheek, in
which, being perfectly smooth and lubricous, it moves
readily, but without synovia, like a rotida in its aceta-
bidum. The upper one projects from the jaw, forms
the segment of a circle, and is concave also on its inner
face. A corresponding more shallow, or, as anatomists
speak, glenoid cavity of the cheek, where it meets the
upper-lip, receives it, and the concave part admits a lubri-
cous ball projecting from the cheek, upon which it turns ^

" A corresponding articulation takes place between the tibia and ■
thigh of some of the Scarabceidce, which will be hereafter described
See Plate XXVI I. Img. 8—11

4.30 EXTERNAL ANATOMY OF INSECTS.

This Structure you will find in the stag-beetle, and some
other timber-devourers. Other Coleoptera have only a
process of a similar structure at each of the dorsal angles
of the base of the mandible, the intermediate one being
wanting; and the articulation does not materially differ,
as far as I have examined them, in the mjmenopera and .
Neuroptera. In the Ortlwptera, the structure approaches
more nearly to that of the stag-beetle, since there are
three prominences: it is thus well described by M. Mar-
cel de Serres: " This articulation," says he, " takes place
in two ways. At first, in the upper surface of the man-
dible, and at its base, maybe observed two small promi-
nences and a glenoid cavity ; these prominences are re-
ceived in two glenoid cavities excavated m the shell ot
the front, as the cavity of the mandible receives a small
prominence of the same part. Below the mandible, and
at its base, there is a kind of condyle, which has its play
in a cotyloid cavity excavated in the shell of the temple,
far below the eye, and at the extremity of the coriaceous
inteo-ument of the head Within the head in this oi^
der, at least in Locusta Leach, is a vertical sept^m which
divides the head into two chambers, as it were, an occi-
pital and a frontal, consisting of a concave triangu ar
stem, termmating in two narrower concave triangiilar
branches, so as to resemble the letter Y, and foi-mmg
three openings, an upper triangular one, andtwo lateral
subquadrangular ones, which last are the cavities tl^t re-
ceive the base of the mandibles. This partition, which I
would name Ccphalophragma, doubtless affords a point of
attachment to many of the muscles of the head. It does

. Comparcason des Organcs dc la Mastication dcs Orthopt^res, 2.

EXTERNAL ANATOMY OF INSECTS.

431

not appear to have been noticed, unless it be synonymous
with the intermaxillai-y arcade of Marcel de Serres*.
Probably a corresponding support to the muscles, &c.
may exist, as we have seen it does in Vesjpa L. in many
other heads of the different Orders, which have not yet
fallen under examination. Many mandibles, as those of
the hornet &c., appear to be suspended to the cavity of
the head on the inside by a marginal ligament suffi-
ciently relaxed to admit of their play : those of the Or-
thoptera, M. Marcel de Serres informs us, are united to
the head by means of two cartilages, the outermost being
much the shortest, to which their- moving muscles are
attached. These he considers as prolongations of the
substance of the mandible <=. The bottom of mandibles,
when cleared of the muscles &c., inclines almost univer-
sally to a triangular form; but in some cases, as in the
stag-beetle, it is nearly a trapezium. I cannot conclude
this subject without noticmg the motions of the mandi-
bles. What the author lately quoted has said with re-
gard to those of the Ortlioptera, wiU, I believe, apply
equally well to all the mandibulate orders. « The arti-
culation of mandibles with the skuU appears to take place
by two points solely; and as these parts only execute
movements limited to a certain direction, they may be
referred to ^2n^Z7/?«M5d,_'phe movements of mandibles
are limited to those from within outwards, and from
without inwards ^" Whether they are restricted fi-om
any degree of vertical motion, has not yet been proved,
as the jaws of vertebrate animals move horizontally as

Comparaison des Organes de la Metrication dcs Orthoptcres
" Sec above, p. 407. note b. Ubi supra, 4. " Ihid. c 5.

432 EX'rr.RNAL v^natomy or insects.

well as vertically— so those of insects may have' some
motion vertically as well as horizontally; and it seems
necessary for some of their operations that they should.
I am not anatomist enough to speak with confidence on
the subject, but the ball and socket articulation at the
lower part of the mandible, and the curving one at the
upper, though a kind ginghjmus, seems to imply a de-
gree of rotatory movement, however slight.

I must next say something upon the general shape of
these organs. Almost universally they incline to a tri-
quetrous or three-sided figure, with their external sur-
face convex, sometimes partially so, and their internal
concave. Most frequently they are arched, curving in-
wards; but sometimes, as m Prionus octangidaris\ a Ca-
pricorn beetle, and others of that genus, they are nearly
straight; and in RUna barbirostris\ a most remarkable
Brazilian weevil, their curvature is outwards. In Pholi-
dotus lepidotm MacLeay, and Lucanus Elephas, two in-
sects of the stag-beetle tribe, they are bent downwards;
and in Lucanus nebulosus K. {Ryssonotus MacLeay) they
turn upwards They are usually widest at the base,
and -row gradually more slender to the apex, but in the
hornet {Vespa Crahro) the reverse takes place, and they
increase in width from the base to the apex: and in the
hive-bee, and others of that tribe, they are dilated both
at base and apex, being narrowest in the middle ; others
are nearly of the same width every where In those
insects that use their mandibles principally for purposes
connected with their economy, they are often more broad

> Oliv. Ins. no. 66. Prionus. f.xiii./. ."vi.
1' Ibid. no. 83. CitrcuHo. t. iv./. 37-

III piopoi tuwj Uj tiuth tlikkiietm, tUmi tliey are In Uiose
wlikJi ube tluijTi piiiicipaJJy lor «jiu>Ucatio/j. In tlic io-
cuiit tribes {hnmla J^eadj), tiiey are c-xtremdy thick
»/«J jjowerliil oigaub, aiid fitted lor their work ol' devat^
lati/jjj; but in tlie glow-worm (iMinj/ip is), tiiey are very
fclemier aiul minute. In those b/iJJiant lieetlfs, the i?z<-
presli^a, i\uty are very short; but in the stag-beetles, ajid
tijose giants in the Caj>ricor/i tribe, the Pno?ii, they are
olLen very h>ng '1 hey eitlier meet at the sumnjit, lap
over ea<:Ji other, crotis each othei-, or are protended
straight Irom the ijead ; as you Imve doubtless observed
iJi the blag-beetle, wlu>se terrific \umiii aie mandibles of'
tins <lescrij>tix>/j, 'I'hese orga/js are usually sipnmetrkal,
but in some instances they are not: thusi/j lihterUjevus,
ii ki/id of du/jg.|>ec'tle, die lelt hand nia/idible is longer
limn tlie right; in CrmjthiLm maxilloms K. {Stapky-
linus L.), a connnon rove-beetle, \n tlxe lelt iiand nian-
dible tlie UHA\i \n the middle is bifid, and in the right
ijand one intiie; aiid in lioLhoccrm K. the majidibie of"
one side, in some sjMicies the dexter, and i/i others the
hinistej-, has two tecHh, and the other /lone.

'J he next circumstance with respect to these organs
whicli demaiids our attention, is the ieeih witli whici»
they are arme<l. These are merely prcx^esses of tlie sub-
btinioj of the mandible, and iiot plaijted in it hy f^wnjjho^
sts ^ as anatomists speak, as they are \n vertebrate ani-
mals. 'I'hey have, however, in their interior, at tJie Imse

• I'or Mandibles of L'k-usUx see Plate Vf. Fio. «. of TMMjwru
Oiiv. Jn,. no. ^. I. If. 1. .A Jiujjresti,, HM. no. W.. I. m.f. 17 . of
Lu^jmu,. Ihul. no. ] . t. i_v, a,iU of Prujnm, J (Ad. no. m. t. u.f. H.

fJompho»u is, when one bone ib i/nifloveaWy fixed in wiother «
a nail nj a hoard,

nr. 'I r -

434. EXTERNAL ANATOMY OF INSFXTS.

-at least, in the Orthoptera, a coriaceous lamina that se-
parates them in some sort from the body of the mandi-
ble \ Many insects, however, have mandibles without
teeth; some merely tapering to a sharp point, others ob-
tuse at the end, and others truncated ^ Of those that
liave teeth, some have them on the inside at the base, as
Manticora, an African tiger-beetle ; others in the mid-
dle, as Stapliylinus olens, a rove-beetle, Lethrus cepha-
lotes, &c.<i; others at the end, as many weevils {Curm-
liQ L.)'=; others again on the back, as the Eutelida, a tribe
of chafers and Lethrus, a beetle just named; others
once more on the lower side of the base, in the form
of a tooth or spine, as in Melitta spmigera, a species of
wild-bee, and some of its affinities S; and lastly, others
on the upper side of the base in the form of a long tor-
tuous horn, as in that singular wasp Sy7iagris cornuta F.
before noticed as a sexual character In the stag-
beetle tribes {Lucanus L.) these teeth are often elongated
into short lateral branches, or a terminal fork They
are sometimes truncated, sometimes obtuse, and some-
times acute.

But with regard to their kind, it will be best to adopt
the ideas of M. Marcel de Serres; for though his re-
marks are confined to the Ortliopter'a, they may be ap-
plied with advantage to the teeth that arm the mandibles

^ Marcel de Serres JiJj s«p-a- 7. . , • . f n

b See Plate XIII. Fig. 7. Kirby ilib«. ^^^^^
J ^ •• t 4- M\ <= Plate XXVI. Fig. 19.

and ^.xii. neutf. 10. r,\ • r i i

0 Oliv. Ins. no. 43. t. i.f. 1 • and no. 3. t.i.f. 1 • b.
e^LATEXXVI.FlG.16,18. ^ Ibid. FiG. 31 •

e Mon. Ap. Angl.lt. iv. Melitta. f. 5— S.
h Drury Ins. ii. t. xlviii./. 3. See above, p.
' Oliv. no. 1. t. v.f. 16. &c. f. ni./. 7-

EXTERNAL ANATOMY OF INSECTS.

435

of insects in general. He perceives an analogy between
those of this Order and the teeth of quadrupeds ; and
therefore divides them into mcisive or cutting, lanim-y
or canine, and molm-y or grinding teeth. He denomi-
nates those incisives that are broad, having m some de-
gree the shape of a wedge, their external surface being
convex, and their internal concave ; whence they are evi-
dently formed for cutting. The laniaries are those which
have a conical shape, are often very acute, and in gene-
ral the longest of any ; and in some insects, as the carni-
vorous Orthoptera (and the Lihellulina\ they cross each
other. The molaries are the largest of all, and their
purpose is evidently to grind the food. There is never
only a single one to each mandible, while the number of
the incisives and laniaries is very variable. As the mo-
laries act the principal part in mastication, they are
nearer the inner base of the mandible or point of sup-
port: they serve to grind the food, which has been first
divided by the incisives or torn by the laniaries. The
carnivorous tribes are destitute of them ; hi the omnivo-
rous ones they are very small, and m the herbivorous
ones they are very large ^ So that in some measure
you may conjecture the food of the animal from the teeth
that arm its mandibles. Of incisive teeth you may find
an example in those that arm the end of the mandibles
of most grasshoppers (Locusia), and of the leaf-cutter-
bees {Megachile Latr.)"; of the laniaiy or camne teeth,
you will find good examples in the mandibles of the
dragon- flies {Libellulina)\ the two external teeth of the

* Comparaison des Organea, &c. 7 — •
Plate VI. Fig. 6. and XIII. Fig. 5. a'".

2 F 2

436 EXTERNAL ANATOMY OF INSECTS.

apex of those of the leaf-cutter bees may be regarded as
between the incisives and kniaries ; and the pointed man-
dibles without teeth may be deemed as termmatmg m a
hniary one ». The lower part of the inner or concave
surface of the mandibles of grasshoppers will supply you
with instances of the molai-y teeth, and the apex, also, ot
those of some weevils, us Curculio Hancoch K.^ But
the most remarkable example of a molary organ is exhi-
bited by many of the Lamellicorn beetles, especially those
that feed upon vegetables, whether flower or leaf.-
Knoch, who indeed was the first who proposed callmg
mandibles according to their teeth, incisive, laniary, or
n^olary, but who does not explain his system clearly,
observed that the mandibles of some Melolonth^ have a
projection with transverse, deep furrows, resembling a
file for the purpose of bruising the leaves they feed upon :
and M. Cuvier, long after, observed that the larv. of
the stag-beetle have towards their base a flat, striated,
,nolary surface; though he does not appear to have no-
ticed it in any perfect insect''. This structure, with the
exception of the ScmMdce and Cetoniada^, seems to
extend very generally through the above tnbe; since it
n.ay be traced even in Geotncpes, the common dung-

» Plate VI. Fig. 12. and XIII. Fig. 5. b'".

: fr„™'.i;at &och had owed this pa« till so.c

I happened to meet w.th ■ ™ ° ^^f„,„,, ,„ ,|,e » ork of

t^h';' r:s itTa; u J, .„.e„ .o.,,

BeUfdge zur Insektengeschchte,
Anal. Comp. iii. SSI—.

EXTfiUNAL ANATOMY OF INSliCTS.

4.37

chafer, in which at the base of one mandible is a con-
cave molary surface, and in the other a convex one, but
without any furrows : a circumstance that often distin-
guishes those that have furrows. — In the Dynastidcc
the affinity of structure with the Melolonthidce &c. is
more pronounced, the furrows to which ridges in the
Other mandible correspond being reduced to one or two
wide and deep ones ; whereas in some of the latter tribe
they are very numerous. These mandibles, in many
cases, at their apex are furnished with incisive teeth to
cut off their food, and with miniature mill-stones to
grind it «. The part here alluded to I call the Mola.

Were I to ask you what your idea is with regard to
the use of the organs we are considering, you would
perhaps reply without hesitation, " Of what possible use
can the^aws of insects be but to masticate their food?"
But in this you would in many instances be much mis-
taken; as you will own directly if you only look at the
mandibles of the stag-beetle— these protended and for-
midable weapons, as well as those of several other bee-
tles, cannot be thus employed. « Of what other use,
then, can they be? " you will say. In the particular in-
stance here named, their use, independent of mastica-
tion, has not been satisfactorily ascertamed; but in many
other cases it has. Recollect, for instance, what I told
you in a former letter, of those larvae that use their un^
guiform mandibles as instruments of motion ^. Again ;
amongst the Hymenopterous tribes, whose industry and
varied economy have so often amused and interested you,

» One of these mandibles is represented in Plate XXVI. Fig.
20. a'", incisive teeth d'". molary plate. Comp. Linn. Tram, ubi
lupr. I. iii./. 4. cab. b vou II. p. 275—.

4.58 EXTERNAL ANATOMY OF INSECTS.

many have no other tools to aid them m tlieir various
labours and mechanical arts : to some they supply the
place of trowels, spades, and pick-axes ; to others that of
saws, scissors, and knives— with many other uses that
might be named. In fact, with the insects of this intire
Order mastication seems merely a secondary/, if it is at
any time their use. Still comprehending in one view all
themandibulate Orders, though some use their mandi-
bles especially for purposes connected with their economy,
yet their most general and primary use is the division,
laceration, and mastication of their food; and this more
exclusively than can be affirmed of the under-jaws {max-
illte). This will appear evident to you, when you consi-
der that insects in their larva state, in which universally
their primary business is feeding, with very few excep-
tions use the organs in question for the purpose of masti-
cation, even in tribes, as the Lepidoptera, that have only
rudiments of them in their perfect state-while the^na^-
ill^ ordinarUy are altogether miapt for such use ihe
exceptions I have just aUuded to are chiefly confined to
the instance of suctorious mandibles; or those which,
beinc furnished at the end with an orifice, the animal m-
sertingthem into its prey, imbibes their juices through
it This is the case with the larv^ of some Dyttsa, He-
rnerobius, and Myrmeleon^; and spiders have a similar
opening in the claw of their mandibles, which is sup-
posed to instil venom into their prey \

Under this head I must not pass without notice an
appendage of the mandibles, to be found in some of die
. In the Myrmcleon, or ant-lion, the suction is promoted by the

action of a piston, that V^^V^ ^''T'l^TTl^l'
b De Geer iv. 38(5— t. xv./. 10. See above, p. 121.

EXTJillNAL ANATOMY OF INSKCTS.

439

rove-beetles {Staphylinidce), as in Ocypics, Slajjhijlmus,
and Creophilus Kirby. In the first of these it is a curved,
narrow, white, subdiaphanous, submenibranous, or rather
cartilaginous piece, proceeding from the upper side of
the base of the mandible ^ ; in the second it is broader,
straighter, and fringed internally and at the end with
hairs ; and in this at first it wears the appearance of be-
ing attached laterally to the mandible under the tooth
but if closely examined, you will find that it is separate :
in Creophilus maxillosus it is broader. This is the part
I have named prostheca. It is perhaps useful in prevent-
ing the food from working out upwards during masticar-
tion.

5. Maxilla The antagonist organs to the mandible
in the lower side of the head, are the under-jaws, or max-
nice— so denominated by the illustrious Entomologist of
Kiel. Linne appears to have overlooked them, except
in the case of his genus Apis, in which he regards them,
and properly, as the sheath of the tongue. De Geer
looked upon them in general as part of the apparatus of
the under-lip or labium ; and such in fact they are, as
will appear when we consider them more particularly.
Fabricius has founded his system for the most part upon
these organs, the principal diagnostic of ten out of his
thirteen Classes (properly Orders) being taken from them;
and m the modern, which may be termed the eclectic, sy-
stem, although the Orders are not founded upon them,
yet the characters of genera, and sometimes of large
tribes, are derived from them : and as they appear less

" Plate XIII. Fig. 7. c".

Oliv. Ins. no, 42. Slaphylinus. t.\.f.\.h.
' Plates VI. VII. XXVI. d'.

440 EXTERNAL ANATOMY OF INSECTS.

liable to variation than almost any other organ, as Mr.
W. S. MacLeay has judiciously observed, there seems
good reason for employing them — it is therefore of im-
portance that you should be well acquainted with them.

Their situation is usually below each mandible, on each
side of the labium: towards which they are often some-
what inclined, so that their tips meet when closed. In
some cases, as in the Predaceous beetles {Carahisl.. &c.),
they exactly correspond with the mandibles"; but m others
their direction with respect to the head is more longitu-
dinal, as in the Hymenoptei-a, &c. In substance they
may be generally stated to be less hard than those or-
gans ; yet in some instances, as in the Libellulina, Ano-
j)lognat1iid(c, &c. they vie with them, and in the Scara-
boeidce and Cetoniadcs exceed them, in hardness. In the
bees, and many other Hymenoptera, they are soft and
leathery. Their articulation is usually by means of the
hinge on which they sit: it appears entirely ligamentous,
and tliey are probably attached to the labium at the
base, or mentum—^i least this is evidently the case with
the Hyvienoptera, in which the opening of the maa:ill(S
pushes forth the labium and its apparatus. In that re-
markable genus related to the glow-worms, now caUed
Phengodes {Lampyris plumosa F.), and in the case-worm
flies {Trichoptera K.), the maxilla appear to be connate
with the labium, or at least at their base.— As to their
composition, tliese organs consist of several pieces or por-
tions. At their base they articulate with a piece more
or less triangular, which I call the hinge {Cardoy. This
on its inner side is often elongated towards the interior

» Plate VI. Fig. 3, 6, 12. VIL Fig. 3. e".

EXTERNAL ANATOMY OF INSECTS.

441

of the base of the labium, to which it is, as I have just
observed, probably attached. This elongate process of
the hinge in Apis, Bombus, &c. appears a separate arti-
culation ; and the two together form an angle upon which
the mentum sits *, and by this the maxilla acts upon tlie
labial apparatus.

The next piece is the stipes or stalk of the viaxilla.
This is the part that articulates with the hinge, and may
be regarded in some cases, as in the Orthoptera &c., as
the whole of the maxilla below the feeler; and in others,
as in the Geotnipidce, Staphylinida: &c., as only the back
of it, the inside forming the lower lobe. This piece is
often harder and more corneous than the terminal part,
is linear, often longitudinally angular, and in the bee-
tribes {Apis L.) is remarkable on its inner side for a se-
ries of bristles parallel to each other like the teeth of a
comb In Pogonophorus Latr., a kind of dor or clock-
beetle, it is armed on the back with four jointed spines,
the intermediate one being forked ^. M. Latreille has
thus described the stipes of the maxilla; of Coleoptera :
" Next comes the stalk," says he, « which consists of
three parts: one occupies the back and bears the feeler;
the second forms the middle of the anterior face, and its
figure is triangular; the third fills the posterior space
comprised between the two preceding ; and is that which
is of most consequence in the use of the maxilla; the an-
terior feeler, where there are two, the galea, and the
other appendages that are of service in deglutition, are
part of that piece

" Plate VII. Fig. 3. a", e". Man. Ap. Angl. i. t, xiii./. I.e.

" Ibid.f. 3. a. « Clairv. Ent, Hclvet, iL 146. t. xxiii./. super, b.

" N. Did, d'Hisl. Nat. iv. 243.

442 EXTERNAL ANATOMY OF INSECTS.

The third and terminal portion of the maxilla is formed
by the lobe, or lobes {Lohi). Tliis may be called the
most important part of the organ, since it is that which
often acts upon the food, when preparing for degluti-
tion. When armed with teeth or spines at the end,
its substance is as hard as that of the mandibles; but
when not so circumstanced, it is usually softer, re-
sembling leather, or even membrane and sometimes
the tniddle part is coriaceous, and the margin membra-
nous. This part is either simple, consisting only of one
lobe, as you will find to be the case with the Hymeno^
jytera, Dynastida, Nemog7iat1ia, and several other bee^
ties ; or it is compound, consisting of two lobes. In the
former case, the lobe is sometimes very long, as in the
bee tribes, and the singular genus of beetles mentioned
above ^ Nemognatha; and at others very short, as m
Hister, &c. The bilobed maxillcc present several difte-
rent types of form. Nearest to those with one lobe are
those whose lower lobe is attached longitudinaUy to the
inner side of the stalk of the organ, above which it
scarcely rises. Of this description is the maxilla m the
common dung-beetle {Geotrupes stercorarius), and rove-
beetle {Staphylinus olensV Another kind of formation
is where the lower lobe is only a little shorter than the
upper: this occurs in a kind of chafer {Macraspis tetra-
dactyla MacLeay).^ A third is where the upper lobe
covers the lower as a shield; as you will find m the Or-

. In Anoplognathus, however, though it has neither teeth nor
spines, it is as hard as the mandibles,
h Sec above, p. 317- ,„
Plate XXVI. Fig. 10, 11. d .e .

H Ibid. Fig. 9. d'", c'".

EXTERNAL ANATOMY OF INSECTS. 44.3

iJioptera order, and theLibelbdina, and almost in Meloe^.
A fourth form is where the upper lobe somewhat resem-
bles the galeate maxilla just named ; but consists of two
joints. This exists in Stai^hylinida:^ &c.'' The last kind
I shall notice is when the upper lobe not only consists of
two joints, but is cylindrical, and assumes the aspect of
a feeler or palpus This is the common character of
almost all the Predaceous beetles {Entomophagi Latr.).
This lobe, which has been regarded as an additional
feeler, is strictly analogous to the upper lobe in other in-
sects, and therefore should rather be denominated a pal-
piform lobe than a. palpus. Where there are two lobes,
the upper one is most commonly the longest; but in
many species of the ti'ibe last mentioned the lower one
equals or exceeds it in length ^.

The lobes vary in form, clothmg, and appendages.
The upper palpiform lobe in those beetles just men-
tioned, in general varies scarcely at all in form ; but the
genus Cychrus (which is remarkable for a retrocession
from the general type of form of the Carabi L. making an
approach towards that of those Hetermnera which, from
their black body and revolting aspect, Latreille has named
Melosomes,) affords an exception, the upper joint being
rather flat, Imear-lanceolate, incurved, and covering the
lower lobe % which it somewhat resembles. The lower

; P^^^^ VI. Fig. 6, 12. d'". e". Oliv. Ins. no. 45. Meloe. t. i.
J. 1. c. These are what Fabricius cdls galeate maxilte, on which he
founded his class Ulonata.

" Plate XXVI. Fig. 11. d'". e'"
Plate VI. Fig. 3. d'".
Clairv. Ent. Helvet. t. i. t. xviii./. super, h.
" Ibid. U XIX. h. This genus may be the analogue of some hetero-

EXTERNAL ANATOMY OF INSECTS.

lobe also in this tribe varies as little as the upper, being
shaped like the last joint of that lobe in Ci/chrus just de-
scribed, except that in Cicindela it is narrowest in the
middle In other tribes the upper valve is sometimes
linear and rounded at the apex, and the lower truncated,
as in Staphylinus olens^; sometimes the upper one is
truncated or obtuse, and the lower acute, as in Trogosita
and Parnus S In Ptinus, another tribe of beetles, be-
fore noticed as injurious to our museums ^ the reverse of
this takes place, the upper-lobe, which is the smallest
and shortest, being acute, and the lower truncated «=. In
Blaps both are acute In Bhipiphoms and Scolytus the
lobes are nearly obsolete. The lower lobe is bifid m
Languria, a North American genus of beetles, so as to
give the maxiUa the appearance of three lobes and m
Eroti/lus, a South American one, the upper is triangu-
lar it is often oblong, quadrangular, linear, &c. m
others.— In those that have only one lobe the shape also
varies. In Gj/rinus, the beetle that whirls round and
round on the surface of every pool, which, though it be-
longs to the Predaceous tribe, has only one lobe, the lobe
represents a mandible in shape of the laniary kind, bemg

merous one yet undiscovered, as Calo,o,na is of Adelium (Kirby Linn.
Trans, xii. t. xxii./. 2.)

» Clairv. Ent.Helvet. ii. t. xxiv./. super.*.

b Plate XXVI. Fig. 11. . ^

. m: i,u. no. 19. Tro^cUa. i. l.f. d. no. 41 ^».Sr,op.. i. ..

^ ^ <! See above, Vol. I. p- »^o-

«' Oliv. Ins. no. 17- Ptimu. t. i./. 1. c.

f Ibid. no. 60. Blaps. t. If- 2. c.

« md. no. 88. Languria. t.lf. 2. c.

h J6kf.no. 89. Erotylus. t. ilf. 12- c

EXTERNAL ANATOMY OF INSECTS.

445

ti igonal and acute • ; and in the AnoplognatliidcCy a New
Holland tribe of chafers, in which it is, as it were,
broken, the lobe forming an angle with the stalk, it is
concavo-convex and obtuse, and somewhat figures a
molary tooth ^. In the first tribe into which the bees
{Apis L.) have been divided {Melitta Kirby), the lobe is
often linear or strap-shaped, and bifid at the apex ; and
in the second {Aph K.) lanceolate and intire <=. In Cero-
coma it is long and narrow ^. More variations in form
might be named, but these are sufficient to give you a
general idea of them in this respect With regard to
their clothings I have not much to obser ve — in exjimin-
ing the Predaceous beetles you wiU observe, that tlie in-
terior margin of the lower incurved lobe is fringed with
stiff brisdes or slender spines, and in many other beetles
either one or both lobes have a thick coating or brush of
stiffish hairs but in several cases only the apex of the
lobe is hairy. In the Orthoptera order, and many of the
Melolonthida or chafers, the whole maxilla is without
hairs, or nearly so.

The appendages of the maxilla; are next to be noticed.
These are prbcipaliy their claws, or laniary teeth ; for
they are seldom armed with incisive or molary teeth.
The whole tribe of Predaceous beetles, with few excep-
tions, have the inner lobe of their maxilla armed with a
terminal claw, which m the Cicinddidce articulates with
the lobe, and is moveable, but in the rest of the tribe is

* Oliv. Ins. no. 41. Gyrinus. t. i.f. 1. e.

^ Plate XXVI. Fig. 13. Hor. Entomolog. i. /. iii./ 2.0, 30. E.
' Mon. Ap. Angl. i. t. ii. Melitta. •». a./. 2. t. v. Apis. «. b./. 4. &c.
Oliv. Ins. no. 48. Cerocoma. t. i./ I.e.

• Plate XXVI. Fig. 10—12.

44G EXTERNAL ANATOMY OF INSECTS.

fixed \ In Phoberus MacLeay the lower lobe has two
spines In Locusta this lobe has three or four spines
or laniary teeth, and in ^shna there are six, which, like
the, claw of Cicindela, are moveable ^ In others both
lobes terminate in a single spine or claw : this is the case
with Pa:villus MacLeay In Passalus, nearly related
to the last genus, the upper lobe is armed with a smgle
spine, and the lower one with twoS Those maxillce that
terminate in a single lobe are also often distingmshed by
the spines or teeth with which it is armed; thus in a
nondescript chafer belonging to the Dj/nastzd^e [Ar-
chon K MS.) it terminates in two short teeth ; in that re-
markable Petalocerous genus Hexodon Oliv. in threeivm,-
cated inciswe ones ^; in Dynastes Hercules in three aaUe
spines Four similar ones arm the apex of the maxilla
in that tribe of Butelidce which have stiiated elytra ; and
five that are stout and triquetrous those of Melolontha
Sti-ma F. Many others have six spines, sometunes ar-
ranged in a triple series \ Besides teeth or spines, m
some cases the lobes of maxillce terminate in several long
and slender Za«m^ or lappets fringed with hairs. At
least those of a Leptura {L. quadrifasciata L.) described
by De Geer, appear to be thus circumstanced. He con-
jectures that this beetle uses its maxilla to coUect the
honey from the flowers

a Clairv. EnL Helvet. ii. Cicindela. L xxiv./. super, b. for Carabi-

Hot. Entomolog. ^. t u./- 1^- ^- ^ ^

d Hor. Entomolog. t. \.J. 6. i^- J
f Oliv. Ins. no. 7. Hexodon. t. i.f. 1. e.
8 Ibid. no. 3. ScarabcBus. t. 1./. 1. f-
u Kirby in Linn. Trans, xiv. 102. t. ui. f. 4. d.
i DeGeerv. 417- <.iv./. 12.

EXTERNAL ANATOMY OF INSECTS. 44.7

As the principal use of the mandibles is cutting and
masticating, so that of the organs we ajre considering
seems to be primarily that of holding the food and pre-
venting it from falling while the former are employed
upon it. I say this is their jprimary use ; for I would by
no means deny that they assist occasionally in commi-
nuting or laceratmg it. In fact, were there no organs
appropriated to this use, and if both mandibles and maX"
nice were employed at the same time in comminuting the
food, it seems to me that it must fall from the mouth.
In a large proportion of msects the lobes of the maxillce
are not at all calculated for laceration or comminution ;
and m those tribes— as the Melolo7ithicUe, Rutelidee, Dy-
nastidce — ^in which they seem most fitted for that pur-
pose, the mandibles have incisive teeth at their apex, and
at their base a powerful mola or gi'inder : circumstances
which prove, that even in this case the busmess of mas-
tication principally devolves upon them.

6. Palpi Maxillares *. There is one circumstance that
particularly distinguishes the maxillce from the mandi-
bles— they are palpigerous, as well as the under-lip. The
feelers, or palpi, emerge usually from a sinus observable
on the back of the maxillce where the upper lobe and
stalk meet. Their articulation does not materially difier
from that of the labial palpi. Each maxilla has properly
only one feeler ; but, as was lately observed in certain
tribes the upper lobe is jointed and palpifonn, which
has occasioned it to be considered as a feeler, and these
tribes have been regarded as having six feelers. The
most general rule with regard to the length of the palpi

• Pirates VI.VII. h".

See above, p, 443.

44S EXTERNAL ANATOMY OF INSTiCTS.

is, that the maxillary shall be longer than the labial; but
the reverse often takes place. In many hees the maxil-
lary consist only of a single joint, and are very sliort .-
while the labial consist oifour, and are very long-: and
in some insects (as in PogonopJwuis Latr.) the four palpi
are of equal length The antennae are most commonly
longer than the palpi; but in several aquatic beetles, as
Elophorus, Hydrophilus, &c., whose antennae in the wa-
ter are not in use, the organs we are considering are the
longest.— As to the number of their articulations, it va-
ries^from one to six ; which number they are not known
to exceed. In each of the Orders a kind of law seems
to have been observed as to the number of joints both
in the maxillary and labial palpi, but which admits of
several exceptions. Thus in the Coleoptera, the natural
number may be set at>.r joints for the maxillary, and
three for the labial palpi: yet sometimes, as m Stenus,
Notoxus, &c., the former have only three]omts, and the
latter, as in Stenus and Tillus, only two. In the Ortho-
vtera the law enjoins>. for the maxillary, and three for
the labial; and to this I have hitherto observed no ex-
ception. In the Hymenoptera, the rule is six ^xAfour,
but with considerable exceptions, especially as to the
palpi, which vary from six joints to ^smgle
one • thus in the hive-bee and the humble-bee, the la-
bials, including the two flat joints or elevators, have four
ioints while the maxillaries are not jointed at all <=. In
Chysis in which the latter consist of>^, the former are
reduced to three. The Libellulina may almost be re-

a Mon. Ap. Angl. I t ix. 2. c. 2. /3./. 2. dg. 4. t. ^IneuLf. 6. d.

EXTERNAL ANATOMY OF INSECTS. 449

gaTded as having no maxillary palpi, since they exhibit
no organ that is distinctly palpiform. It seems to me
that the upper lobe of their maxilla, which articulates
with the stalk in the same manner as a feeler, m.iy
be regarded as an instance in which that lobe and the
feeler coalesce into one; and the mucro that proceeds
from the lobe has tlie aspect of an emerging feeler, and
corresponds somewhat with tlie labial one above no-
ticed". In the remainder of the Ncuroptera and the
Trichopta-a, the prevailing number is Jive and three.
In Uie latter there are exceptions, which will furnish
good characters for genera. In the Lepidoptera we find
fwo, and sometimes thrce^ the maxillary being very mi-
nute ^ The Diptcra Order presents two tribes in this
respect quite distinct from each other. The most natu-
ral number of joints in the maxillary palpi of the Tipu-
lidce, Cidicidce, &c. h four ov five: the last joint, how-
ever, in Tipula, Ctenocera, &c. like that of the antennse
in Tabarius L., appears to consist of a number of very
minute joints <=; but in the Asilid^ and Muscidcu^ &c., the
number fwo seems to be most prevalent^. The labial pal-
pi in this order are obsolete.— As to shape, the maxillary
palpi, as well as the labial, are usuaUy filiform; but in
the weevil tribes {Curculio L.) they are most commonly
very short and conical - in the chafers {Scarabceus L.)
they usually are thickest at the apex f; in Megachile and
Euglossa, wild bees, they are setaceous, growing gradu-

» Plate VI. Fig. I2.b".r".

. Savigny Anim. sam Vertebr. I. j. 29—

uT."-'; °* . ' Geer vi. t. xix. / 4. d.

c ^l^'d./.:xy.8.ii.t. xii./20.7.. t. xiv./:]5.ii.
Platx XXVI. Fig. 6. / ii,,^. 5^

VOL. nr. 2

450' EXTERNAL ANATOMY OF INSECTS.

ally more slender from the base to the smnmit* : a tribe
of small water-beetles {Halijdus), the saw-flies {Ten-
thredo L.), and several other Htjvienoptera, have them
thickest in the middle K Their most important part,
however, and that which varies most in form, is the /^r-
wmaZjoint:— of this I have already related some singular
instances S and shall now describe a few more. This
joint is sometimes acute, at others blunt, at others trun-
cated: in figure it is ovate, oblong, obtriangular, hatchet-
shaped, lunate, transverse, conical, manmiiUate, subulate,
branched, chelate, laciniate, lamellate, &c. &c.d: terms
which I shall more fully explain to you hereafter, and
which I only mention here to show the numerous varia-

a My Man. Ap. Angl. i. t. x. Api.. **. c 2. B./. 3. a. and d. 1.

V clairv. Ent. Hclvct. ii. t. xxxi./. siipcr. b. Man. Ap. Angl. i. L xiv.
/. 1. 7j. /. 3, 5. c.

c See above, p. 317. , , , .,, ^„ „„i -

" Plate XXVI. Fig. 1. As the very remarkable maxillary palpi
of that extraordinary Coleopterous genus Atractocerus seem not to
have been so fully described as they deserve, I ^^^f /^^.^^^ f ^
nute detail of their coitposition. They consist >";;J"-^^
first is wide and short, and somewhat platter-shaped; the jcmid is
xnuch smaller and shorter: the third is

like a shallow bowl: towards the breast this joint is ele ated and
on the elevated edge sits the last joint, which - ^^-^l^X^^^f
. rest taken together. In my specimen it pomts towards the breas .
its under side is entire and slightly curved, but m the upper s de are
two rows of lamelte (b), placed alternately nme on each ^^de, Mth an
odd one at the end : these lamelte are full of minute papilte, and
ilw croif^^^ sid-e next the mouth. From between t e first
a slender exarticulate hairy branch or appendage '^^'^S^]^'^';^ '^^^
VZLvh aright angle with the main stem. The lakalpalpt
':^:::^r^ of Jjomts ; tl. two fu-st v.-y
large, ovate, and acute. This description is not taken on A.^
daMdes, bnl from a Brazilian species more than five times its size,

which I have named A. Gigas.

EXTERNAL ANATOMY OF INSECTS. 451

tions as to figure, of which this joint exhibits examples.
The palpi in general at their vertex are often rather con-
cave; and this concavity is formed by a thin papillose
membrane, which it is supposed the animal has the
power of pushing out a little, so as to apply it to sur-
faces. The prima7-y use of the palpi of insects will be
considered when I treat of their senses; but they proba-
bly answer more pui-poses than one. For instance, when
I was once examining, under a lens, the proceedings of
a species of Mordella, which was busily employed m the
blossom of some umbelliferous plant, it appeared to me
to open the anthers with its maxillary palpi, and they
often held the anther between them : when not so em-;
ployed, they were kept in intense vibration, more than
even its antennae ; mid at the same time, as far as I could
judge, an Elata- made the same use of them.

7. Lingtia \~This name was applied by Linne to the
part in insects representing the tongue in vertebrate ani-
mals ; and as it performs most of the common offices of
a tongue, and the pharynx is situated with respect to it,
as we shall presently see, nearly as it is in those ani-
mals, thisre seems no more reason for giving it a new""
name, than there is for giving a new name to tlie head
or legs of insects, because in some respects they differ
from- those of the higher animals. I shall not therefore
call it Ligzda, with Fabricius and Latreille, nor Labium,
with Cuvier and others, but adhere to the original term,
which every one understands.

The tongue lies between the two ^/>s— the labrum and
labi2im. On its upper side, at the base, it meets the pa-

^ Pi-Aii: VI. VII. xxvr. e.

452 EXTERNAL ANATOMY OF INSECTS.

late or roof of the mouth, below which it is attached, it
may be presumed, by its roots to the crust of the head,
on each side the pharynx or swallow ; and on its lower
side, in many cases, it is attached to the labium, and that
very closely, so as to appear to be merely a part of it,
and to form its extremity: but in the Orthoptera and
Libellulina, it is more free, and in form somewhat re-
sembling the tongue of the quadrupeds ^— In substance
the tongue varies. In general it seems something be-
tween membrane and cartilage ; but in the Predaceous
beetles, in which it is not covered by the labmn, it ap-
proaches nearer to the substance of the general inte-
gument, and in Aiithia F. it is quite hard and horny
that just mentioned of the Orthoptera and Libellulina
is more fleshy". With regard to its station, in many
cases, as in the instance just named, in the Lamellicorn
tribe {ScarabcEUS L.) and others, it is, when unemployed,
concealed within the mouth; the lips, mandibles, and
maxillae all closing over it. The tongue of some Hy-
menoptera also is retractile within the mouth. " When
ants are disposed to drink," says M. P. Huber, " there
comes out from between their lower jaws, which are
much shorter than the upper, a minute, conical, fleshy,
yellowish process, which performs the office of a tongue,
beino- pushed out and drawn in alternately: it appears
to proceed from the lower-lip.-This lip has the power
of moving itself forwards in conjunction with the lower
iaws- and when the insect wishes to lap, all this appa-
ratus moves forward; so that the tongue, which is vei-y
short, does not require to lengthen itself much to reach
a Plate VI. Fig. 6, 12- e'. Cuvier AnaU Compar. iii. 347.
•» Cuvier Ibid.

EXTERNAL ANATOMY OF INSECTS. 4.5$

the liquid \" M. Lamarck thinks that the labmm of
insects lias a vertical motion {de haul en has ou de has
en hatit)^. This it certainly has in some degree; but it
has also, as in the above case, a more powerful horizon-
tal one, which is produced, in Hymenoptera at least,
by the opening of the maxillae — as I have already ob-
served ^.

I have little to say with respect to the structure of the
tongue : it generally seems to be without articulations ;
but in many bees it articulates with the labium where it
enters it, so as when unemployed to form a fold with it.
In the hive-bee it terminates in a kind of knob or button,
which has been falsely supposed to be perforated for im-
bibing the honey by suction. The upper part of this
tongue is cartilaginous, and remarkable for a number
of transverse rings : below the middle, it consists of a
membrane, longitudinally folded in maction, but capa-
ble of being inflated to a considerable size : this mem-
branous bag receives the honey which the tongue, as it
were, laps from the flowers, and conveys it to the j)ha~
rynx"^. In Stenus this organ is retractile, and consists
of two joints ^

The shajpe of the tongue of insects probably varies as
much as any other part; but as it is apt to shrink when
dried f, and is not easy to come at, we know but little of
its various configurations :—m the bees it is very long,
in most other insects very short. Though frequently
simple and undivided, in many cases it presents a diffe-
rent conformation. Thus in the saw-flies {Tenthredo L.)

" Huber Fourmk, 4-. " Anhn. sans Vcrtebr. iii. 304.

See above, p. 440. .t Reaum. v. 309- .

• Plate XXVI. Fig. 23. ' Clairv. Ent. Helvet. ii. Prcf. xxii.

4-54 EXTERNAL ANATOMY OF INSECTS.

it terminates in three equal lobes- in Stomis and Geo-
trupes in three unequal ones, the intermediate being very
short''; in Carahus, in three short teeth - in Pogonopho-
rus it represents a trident in the wasp it is bifid, each
lobe being tipped with a callosity-, in Melolontha SUgma
it is bipartite in Elaphrus, the analogue of the tiger-
beetles, it terminates in a single tooth or point; in the
aquatic beetles, D:ijtiscus U it is quadrangular and with-
out teeth s; in some Ichneimonidce it is concavo-convex,
and forms a demitube; and in others it is nearly cylin-

In many insects it has no hahs, but in the Predaceous
beetles it generally terminates in a couple of bristles
In the hive- humble- and other bees, it is extremely
hairy a circumstance which probably enables it more
effectually to despoil the flowers of their nectar. In Geo-
tncpes stercm-ariics, the common dungchafer, and Melo-
lontha Stigma lately mentioned, the lobes of the tongue
are fringed with incurved hairs'; and in jEsJina it is
hairy on the upper side, each hair or bristle crowmng a
minute tubercle. In many cases the tongue is attended,
and sometimes sheathed at the base, by two usually mem-
branous appendages:-these the learned Illiger has deno-

• Kirby Mon. Ap. Angl. I t. xiv. (1) 3. b.

» Plate XXVI. Fio. 24. e'. Clairv. nh supr. L xx. c.

^^^ySZ "^^'CB)'!^^ - The lateral pieces in the tongue
in'F^LlS wLnr.^^^^^^ but they ai-e

rather Pam^^^. , ^^^.^^^

J, 1 . «.

EXTERNAL ANATOMY OF INSECTS.

4.55

minated paraglossa ; and I shall adopt his teriji. You
will find them frequently attached to the tongue of the
Predaceous beetles and to that of many Hymenopta-a.
In the hive-bee and humble-bee they are short, and take
their origin within the labial feelers ^ : in Euglossa, an-
other bee, they are long, involute at the tips, and, what
is not usual with them, very hairy = : in the' wasp, like
the lobes of the tongue, they are tipped with a callosity.

Under this head I may observe to you, that the in-
sects whose oral organs we ai'e considering besides a
tongue appear likewise to be furnished with a palate {Pa-
latum). This, though a part of the roof of the mouth,
is not precisely in the situation of the palate of vertebrate
animals, since it seems rather the internal Immg of the
lahnm. If you take the common dragon-fly {Mshna
viatica), you will find that the under side of this part
and of the rhinarium is hned with a quadrangular fleshy
cushion, beset, Uke the upper surface of the tongue, with
minute black tubercles, cro\vned with a bristle. This
cushion is divided transversely into two parts by a de-
pression; the anterior or outer piece being attached to
the labrum, and the other piece to the rliinarium. The
former has a central longitudinal cavity, black at the
bottom, on the sides of which the tubercles are flat and
without a bristle. From its base on each side a spini-
form process emerges, forming a right angle with it.
These processes seem the antagonists of those mentioned
above that emerge from the labium. Tlie posterior or

Plate XXVI. Fig. 28. i".
" Kirby Mon. Ap. Angl. i. /. xii. neut.f. 1. h h. I. xiii./. l.ff.
<■ Ibld.Lx.**.d, \.f.2.bb.

See above, p. 425.

456 EXTERNAL ANATOMY OF INSECTS.

inner piece has on each side a roundish space, attached
to the under surface of the two sides of the rhinarmm^
beset also with bristle-bearing tubercles. You will find
something similar lining the labrum and 7iasris of some
Coleoptcra,— -say Geotmpes, Necrop?iorus, and Dytiscus.
The first piece I regard as the analogue of the palate, and
the second as connected with the sense of smellmg. In
Necrophorus the circular pieces are covered with a finely
striated membrane, and in D^tiscus each has a little
nipple.

8. Pharynx^. --On the upper side of the tongue, usu-
ally at its base or root, is the pharynx, or aperture by
which the food passes from the mouth to the oesophagus.
This orifice, which is situated with respect to the tongue
of the Orthoptera and Libellulina nearly as in those in-
sects (at least as far as I have been able to examine them),
whose tongue is called a ligula or lahmm,-oi course ex-
ists m all the mandibulate Orders whose mouth we are
now considering. In the Hymcnoptera it is covered by a
valve, the Epipharynx of Savigny ; and it appeared to me
to be so likewise m one of the Harpalid^r that I exammed.
The formation seems different in Geotrupes, as far as I
can get an idea of it; but it is so difficult to examine the
interior of the mouth without laceration of some of the
parts, that I can only tell you what the appearances were
fn one instance, upon removing the labrum from the man-
dibles- and in another, separating the whole apparatus
oUlJ labium, including the maxilla, from the manMles
and labrum. In the former case, the mandibles comcided

» Plate YII. Fig. H. f.

EXTERNAL ANATOMY OF INSECTS. 457

at the base, the two molary plates {molce), which in this
genus are narrow, transverse and not furrowed, are so
applied as evidently to have an action upon each other,
as the mandible opens and shuts, proper for trituration.
Within these is the base of the tongue, under the form
of a ventricose sack. The upper part of this last organ,
which forms the internal covering of the labium, appears
to consist of three (in the recent insect Jlcshy) lobes, the
middle one being bent downwards internally, so as to
form a kind of sloping cover to an orifice in tlie part
I call the base. After two or three days, the tongue
shrinks and dries to a hard substance; — between the man-
dibles and the base of the tongue I could not discover
the pharj/jix. The above apparent opening covered by the
tongue was the only one I could perceive. In the latter
case, the form and structure of the base of the tongue is
more visible: it is an oblong ventricose tubular sack,
projecting above anteriorly into an acute angle formed
by a fine white membrane, most beautifully and deli-
cately striated with oblique stria?, to be seen only under
a powerful lens : on the anterior side of this sack are two
parallel cartilaginous ridges close to each other, fringed
with short hairs, which take then- origin from the angle.
I could not be certain whether the orifice covered by
the intermediate lobe was only apparent, or real; but I
did not succeed in my endeavour to find any other pha-
rynx, though from the molary structure of the base of
the mandibles one may conjecture that there must be one
situated at the base of this sack to receive the food they
render after trituration. The excrement of this animal
is not fluid. In the Libelliilina the pharynx seems
closed by two valves meeting. This part in Hymcno^

458 EXTERNAL ANATOMY OF INSECTS.

;ptera, and probably in other Orders, has the aspect of
being cartilaginous and fitted to sustain the action of the
substances that have to pass through it ^

The EpipJiarynx is a valve, called by M. Latreille
suUahnm {sous lahre''), attached by its base to the upper
margin of the pharynx, or that next the lah'um. In
the bees it is said by Reaumur to be of a fleshy substance,
and capable of changing its figure. He seems to think
it the real tongue oiihe bee but as it does not appear
to have any of the uses of a tongue, and merely closes
the orifice of \he mouth, it surely does not merit that
name. M. Savigny calls it a membranous appendage
which exactly closes the pharynx^. De Geer has exa.-
xnm^^ t\veepipharynx of the wasp, which he describes as
of a scaly substance, and regards merely as the cover of
the part just named

With' regard to the Hypopharynx, which Latreille con-
siders as a support and appendage of the epiplmrynx, I
have Uttle to add to the definition I have given of it above.
In the Libdlulina the base of the tongue terminates
towards the pharynx a fleshy cushion, armed at each
angle next to that part with a short hard horn or tooth
of a black colour. This cushion, I suppose, mo^Yhe ^xi^-
■ logoxxsto the hypopharynxoiM. Savigny^. On the oppo-
site sid6 the pharynx is closed by another fleshy cushion
{epipharynx?\ which appears to line the nose, behind
those two mammillae before described s, which form the
internal covering of the rhinarium.

^ Reaum. v. 317- Organisation extencur dcs Ins. 184.

^ Ubi supra. ^ Amm.samVcrtebr.\\.\^.

e Dc Gcer ii. 778— /. xxvi./. 11. m. Plate \ II. tic. Z. k .
t Ubi supra. » See above, p. 455.

EXT ERNAL ANATOMY OF INSECTS. 459

Before I call your attention to what I would denomi-
nate an imperfect mouth, in which some one or more of
the seven organs above enumerated exist under another
form, or only as rudiments, — I must say something upon
the mouth of the Myriapods and Arachnida, m which
there seem to be redundant organs of mandu cation. —
M. Latreille, in the Essay lately quoted, in which,
though some of his notions seem fanciful, he has shown
a vast depth and range of thought and research, has as-
serted,— from the admu-iable and curious observations of
M. Savigny, and those which since their publication he
has made himself, — that the masticating organs of an-
nulose animals (called by him condylopes) are a kind of
legs^. And M. Savigny, whose indefatigable labours
and imparalleled acuteness have opened the door to a
new and vast field in what may be denominated analo-
gical anatomy, — ^has observed, that with certain Apiro-
pods^ the organs that serve for manducation do not dif-
fer essentially from thoie which, with the other Apiro-
■pods nnd. the Hcxapods, serve for locomotion'^', ancy the
•unguiform mandibles of the larvae of certain Diptera,
you have before been told, are used not only in mandu-
cation, but also as legs ^. These remarks will satisfac-
torily prove to you, that organs which at first sight pos-
sess no visible affinity or analogy — as for instance, jaws
and legs — may, if traced through a long series of beings,
exhibit a veiy great One ;— and will lessen your surprise

^ Organisation &c. 182.
Under this name M. Savigny includes the Myriapoda, Arach-
nida, and Crustacea. Anim. sans Vcrtcbr. I. i. 40.
"= Ibid. 43.

Vol. II. p. 275—. Also see above, p. 121—.

460 EXTERNAL ANATOMY OF INSECTS.

when you find, that in certain tribes such commutations
of organs and their use take place.

The following is the structure, as to its organs, of the
mouth of the myriapods, as exhibited by the centipedes
{Scolopendridce). The part which appears to perform the
office of the upper lip (but which M. Savigny regards
as the nose, calling it the chaperon,) is a transverse piece
with a deep anterior sinus, in the centre of which is a
minute tooth \ This piece is separated fi-om the fore-
part of the head by a suture; but it probably is not move-
able: however, it covers the mouth, and may be regarded
rather as analogous to the labrum. Below this are two
mandibles, armed at their end with five sharp triangular
teeth ^ under which are the maxilla, terminating in a
moveable concavo-convex lobe, resembling the valve of
a bivalve shell <=; and between them is the labium, of a
rhomboidal shape, divisible into two lobes, attached la-
terally to themaxiUse: these lobes M. Savigny terms the
second maxilla, forming with the others, according to
him, the labium''. Affixed to the base of this labium, or
covering it on the outside, are a pair of pediform palpi,
which he considers as the first auxihary labium, and re-
presentative of the first pair of legs of hexapods and Mi ^
I imagine them to be also the analogues, in some degree,
of th^ labial palpi of a perfect mouth. The last of the
organs in question is a large rhomboidal plate affixed to
the first apparent segment of the trunk, crowned at its
vertex with two truncated denticulated teeth, and fi'om

« Anim. sans Vertcbr. I. i. t. ii.f. 2. a. a .

b Plate VII. Fig. 13. c'. --Ibid.d.

" Anim. sans Vertcbr. I. i. lOG. Plate VII. I'lc. lo. b .

• Ubi supr. 45 — .

EXTERNAL ANATOMY OF INSECTS. 461

the upper sides of which emerge a pair of moveable or-
gans terminating in a powerful incurved claw, and which
entirely covers all the other parts of the mouth ^. This,
M. Savigny deems as a secojid auxiliary labium^ and the la-
teral organs of prehension, — which may be regarded each
as a kind of maxillary hand, and as the only representa-
tives jn this tribe of the maxillary palpi, though widely
different, — he looks upon as really analogous to the second
pair of legs in lulus and the hexapods'^. These two pairs
of pedipalpes (to use an expressive French term) show
their relation to legs by their general structure, and their
analogy with palpi by their use as oral organs, though
belonguig to the trunk : so that here we see the legs and
their-appendages assume a material function in mandu-
cation, forming a singular conti'ast to what we had ob-
served befoi'e with regard to ma?idibles becoming instru-
ments of locomotion. The mouth of the lulidcs, with lit-
tle variation, is upon the same plan'^ with those here de-
scribed.

The next type of form with regard to the oral organs
is that of the Arachnida. In these, as you know, the
head is confounded with the trunk ; so that they are a
kind of Blemmyes in the insect world. Their organs of
manducation, amongst which there is no lahrum or upper
lip, are, in the first place, a pair of mandibles planted
close and parallel to each other in the anterior part of
the head, which they terminate. In the spiders they con-
sist of two tubular joints, of which the first is much the
largest, more or less conical or cylindrical, and armed

» Plate VII. Fig. 11./', a".
' Ibid, 44—.

Uhi supra, 45.

4.G2 EXTERNAL ANATOMY OF INSECTSi

underneath with a double row of stout teeth; and the
terminal one is more sohd and harder, in the form of a
very sharp crooked claw, which in inaction is folded on
the first joint between the teeth. Under its extremity on
the outside is a minute orifice, destined to transmit a ve-
nomous fluid, which is conducted there by an internal
canal from the base of the first joint, where is the poison-
bag \ In the scorpion and harvest-man {Phalangium)
th^ mandible consists of two joints terminated by a chela
or double claw, the exterior one being moveable ^—
M. Latreille, as has been before observed, regards these
not as representatives of the mandibles of hexapods, but
as replacing the interior pair of antennae, in the situation
of which they are precisely placed, of the Cnistacea<^-.
and M. Savigny is of opinion that the Arachnida may m
some sort be defined as Crustacea v^xihont ^ head, and
with twelve legs, of which the two first pair are converted
into mandibles and via<,illcE^. From the situation of the
organs in question, the first of these opmions seems pre-
fer'lble; but the conversion of the legs in other cases, at
least the coxce, into organs of manducation, gives some
weight to the last. With regard to their use, it is said
to be to retain the insect which the animal has seized,
and to facilitate the compression which the maxillae exer-
cise upon it for the extraction of the nutritive matter ^
If this be correct, in this respect the mandibles may be
said to represent the maxillce of the mandibulate hexa-
pods ; and, vice versa; the sciatic maxillae, as they have

a N.I)ict.<rmst.Nat.\\.m-^ Plate Vll. Fig. lO. C

^ Dc Geer t. xl./. 4. t. x./. 7, 8. Sec above, p. 18, 30

Savigny Anm. snm Fcrtcbr. I. i. 02.
« N. DicL <rHkl. Kcil. ii. 277.

EXTERNAL ANATOMY OF INSECTS. 463"

been denominated of the Arachnida, their mandibles.
The palpi are pedifoi'm, and the first joint of the coxa,
or hip, acts the part of a maxilla : — this is composed of
a single piece or plate, more or less oval or triangular,
sometimes straight and sometimes inclined to the labium,
with the interior extremity very hairy. The labium con-
sists also of a single piece, and is only an appendage of
the anterior extremity of the breast. The interior of
the mouth, or palate, presents a fleshy, hairy, linguiform
piece, which is usually applied to the internal face of the
labium. An opening is supposed to exist in its sides, for
tlie transmission of the alimentary juices ^. If you ex-
amine the under side of the body of a scorpion, you will
find that not only the palpi, but the two anterior pair of
legs, by means of their coxce, are concerned in mandu-
cation : so that these insects have in fact three pairs of
maxillae — a circumstance that M. Savigny has obsei-ved
to take place also in the harvest-men {Phalajigium L.) <=.
The palpi of the scoi-pion, which may be called its hands, '
like the anterior legs of the lobster and crab, terminate,
in a tremendous chela or forceps, consisting of a large
triangular joint, armed at the end with a double claw
internally toothed ; the exterior one of which, contrary '
to what takes place in the animals just named, is move-
able, and not the interior ^,

Having given you this full account of the trophi of
those animals that have all the organs of manducation
developed, I must next advert to those in which one part

^ N. Diet. cPHint. Nat. ii. 270. " IMd.

' Ubisiipr. 58. ■> Plate XV. Fig. 7.

464? EXTERNAL ANATOMY OF INSECTS.

receives an increment at the expense of others, and the
whole oral machine is fitted for suction.- or where some
parts appear to be deficient, so that this may be called
an imperfect mouth. At first sight one would regard the
tropin of a hee as of this description; but this is not the
case, since it has all the ordinary organs, though the
tongue is unusually long, and looks as if it was made for
suction ; which, however, as you have been informed, is
not the case.

There are fve kinds of imperfect mouth to be met
with in insects that take their food by suction, each of
which I shall distinguish by a separate denomination.
The first is that of the Hemiptera Order -.—this I term
the Promuscis; the second is that of the Diptera, which
with Linn6 I c^W Proboscis : the third, peculiar to the
Lepidoptera, is with me an Antlia; the fourth, which I
name Rostrulum, is confined to the Aphaniptera order,
or genus Pulex L.; and the last is Eostellum, which I
employ to denote the suctory organs of the louse tribe
{Pediculidcje). *

1. Proimscis\—The organ we are first to consider
has usually been denominated Bostrim : but since that
term is likewise in general use for the snout of insects of
the weevil tribes {Curculio L.), I think you will concur
with me in adopting the. one here proposed, for the very
different oral instruments of the Hemiptera. Illiger has
employed promuscis to denote those of hees"^: but since, as
I have just observed, they consist of all the. ordinary or-
gans, they seem to require no separate denomination :

» Plate VI. Fig. 7-9. a', b', C, d'. » Magaz. 1806.

EXTERNAL ANATOMY OF INSECTS.

465

the term, therefore, may be applied to represent a diffe-
rent set of trophic without any risk of producing confu-
sion. This part consists of Jive pieces ; viz. a minute,
long, conical piece, commonly very slender, which covers
the base of the proinusch, and represents the lahrum ^ ; a
jointed sheath {vagina\ consisting of either three or four
jomts, the analogue of the labium^ and four slender rigid
lancets {scalpella\ the two exterior ones, according to
M. Savigny, representing the mandibles, and the inter-
mediate pair the maxillce By the union of these four
pieces a suctorious tube is formed, which the animal in-
serts into the substance, whether animal or vegetable,
the juices of which form its nutriment. These pieces are
dilated at their base, and serrated at their apex; and the
two central ones, though at their origin they are asun-
der, form one tube, which has often been mistaken for a
single piece. A pharynx and tongue have been disco-
vered by M. Savigny in this apparatus; who thinks that
in ISfepa there are also rudiments, but very indistinct, of
labial palpi: so that the maxillary palpi seem to be the
only part absolutely wanting <=.

The Promuscis when at rest is usually laid betAveen
the legs; but when employed, in most cases its direction
is outward. In the genus Chermes L. {Psylla Latr.) the
origin of the proynuscis has been supposed to be in the
breast; but if closely examined, this anomaly in nature
will be found not to exist. If you take one of these in-
sects, the first thing that strikes you upon inspecting the
head, is a pair of remarkable conical processes into which

» Plate VI. Fig. 7. a',

^ Ibid. Labium b'. Mandlbulac c'. Maxillae d'.
Savigny Anim. sans VeHebr. I. i. 37.
VOL. HI. 2 II

EXTKIINAL ANATOMY OF INSECTS.

the front appeal's to be divided. Look below these, aiul
you will there discover the upper-lip : and from this you
may follow the promiiscis till it gets beyond the forelegs,
when it takes a direction perpendicular to the body ^ ; a
circumstance which has given rise to the above false no-
tion. Though in Coccus^ C/iermes, &c. this instrument is
short, in some Aphides it is longer in proportion than in
any other insect. In A. Qiiercus it is three times the
length of the body ; so that when folded, it stretches out
beyond it, and looks like a long tail^; and in A. Ahictis
it even exceeds that length ^.

ii. Proboscis ^. — Linne long since, and after him Fa-
bricius, has employed this term to designate the oral in-
struments, or rather their sheath, in the Miiscida and
some others, calling the same organ, when without fleshy
lips, rostrum and haustelhm: but as the parts of the
mouth in all true Diptera (for Hippohosca and its affinities
can scarcely be deemed as co-ordinate with the rest), are
analogous to each other; although in some they are stiff
and rigid, in others flexile and soft, and in CEstrus (ex-
cept the palpi) mere rudiments,— the same appellation
ought to designate them all. I am happy to find that
M. Latreille agrees with me in this opinion ; and to his
sensible observations on this head, if you wish forfurdier
information, I refer you ^ The mouth of Dipterous in-
sects appears to vary in the number of pieces that itpre-

^ De Geer iii. 137—. t. ix./. 4.
»> Reaum. iii. 335. t. xxviii./. 8—14.
<■ De Geer iii. 117- t.Vm.f. 32. b.
«> Plate VII. Fig. 5, 6. a', b', c', d'.
« N. Diet. d'Hisl. Nat. iv. S53.

EXTERNAL ANATOMY OK INSECTS. 167

sents ; but in all, the theca or sheath is present, which re-
presents the labium (including the mentum) of the man-
dibulate Orders It consists of three joints, the last of
which is formed by the liplets {Labella), Those in the
MuscidcE are large, turgid, vesiculose, and capable of
dilatation ; in the BombylidcE and other tribes they are
small, slender, long and leathery, and sometimes re-
curved. The second joint or stalk, which may be said
to represent the mentum, the liplets being properly in a
restricted sense the analogue o^ihelabium, its sides being
turned up, forms a longitudinal cavity, which contains
the Jiaustellum. The upper piece of this, the valviila, is
long, rigid, and very sharp, representing the lahrum ^.
Beneath this cover, in the above cavity, are the lancets ;
which, as far as they are at present known, vary in niun-
ber and form : sometimes there are Jive of them, some-
timesybwr, sometimes two, and sometimes, it should seem,
only owe=. In the gnat {Culex) they are finer than a
hair, very sharp, and barbed occasionally on one side''; -
in the horse-fly {Tabanus L.) they are flat and sharp like
the blade of a knife or lancet ^ In this tribe the upper
pair, or the knives {Cultelli), represent the mandibles;
the lower pair, or the lancets {Scalpella), usually palpi-
gerous, the maxillce ; and the central one the tongue. In
the horse-fly Reaumur has figured only four, exclusive
of the labmm and labimi ; but in a specimen I have pre-

" Plate VII. Fig. 5, 6. a'. t Ibid.

•= Reaum. iv. t. XVI. Fig. 13. z.
Authors are not agreed as to the precise number of lancets con-
tained in a gnat's proboscis. Swainmerdam affirms there are six, in-
cluding the labrum. i. 156. b. t. xxxii./. 3. Reaumur could find only
five. iv. .597—. t. xHi./. 10. And Leeuwenhoeck only four.

' Plate VII. Fig. 5.

2 H 2

4G3

EXTERNAL ANATOMY OF INSECTf5.

served there appear to hejve, one of which, as slender
as a hair, I regard as the analogue of the tongue —
When the lancets are reduced to two, they probably re-
present the maxilla;, the mandibles being absorbed in
the lahruvi ; and where there is only one, the maxillffi
also are absorbed by the labium, which then bears the
palpi, the lancet representing the tongue The lancets
are so constructed in iTiany cases, as to be able by then-
union to form a tube proper for suction, or rather for
forcing the fluid by the pressure of the lower parts to the
pharynx Labial paljn appear not usually present in
the proboscis; but M. Savigny thinks he has discovered
vestiges of them in Tabanus^. In this genus the maxil-
lary ones are large, and consist of ^wo joints ^ The pro-
boscis is often so folded, as to form two elbows; the base
forming an angle with the stalk, and the latter with the
lips, so as in shape to represent the letter Z, only that the
upper angle points to the breast, and the lower one to
the mouth : this is the case with the flesh-fly and many
others. In other flies, as Conofps and Stomoxys, whose
punctures on our legs so torment us ^ there is only a
single fold, with its angle to the breast. proboscis is
received in a large oblong cavity of the underside of the
anterior part of the head.

» Plate VIT.Fig. 5. This figure is copied from Reaumur, and
was ent^raved before this discovery was made.

b M Savigny is of opinion that the central lancet or lancets re-
preseni the Epivkaryn. and Hypopnaryn. ; for which he does not
state his reasons: but as these are properly covers of the pharjnx.
the idea seems incorrect. Ubi siipr. 15.

c N. Diet. d'Hid. Kaf. ix. 489. and iv. 2o3-.

mis.pr.S6. * Ibid. /.w./. 1.0.0.

f Vol.. I. p. 48, 110—.

EXTKUNAL ANATOMY OF INSECTS. 469

It may here be observed, that in the promuscis tlie
elongation of the organs seems to be made chiefly at the
expense of all the palpi, but in the proboscis at that of
the labial only; and in some cases at that also of the
mandibles or maxilla:, — the former merging in the la-
brum and the latter in the labium.

111. Antlia — The third kind of imperfect mouth is tliat
of the Lepidoptera, which I have called A7itlia. Fabri-
cius denominates it litigna,- but as this organ has no ana-
logy with the real tongue of insects, this is confessedly
improper, and it appeared necessary therefore to exchange
It for another denomination : I have endeavoured to ap-
ply a term to it that indicates its use— to pump up, name-
ly, the nectar of the flowers into the mouth of the insect..
On a former occasion I described to you the structure of
this instrument but further discoveries \vith regard to
it having since been made by MM. Savigny and La-
treille, I shall here give you the result of their obsen-a-
tions. The former of these able physiologists has de-
tected in the mouth of the Lepidoptera rudiments of al-
most all the parts of a perfect mouth. Of the correct-
ness of this assertion you may satisfy yourself, if you con-
sult his admirable elucidatory plates, and compare them
with the insects. Just above the origin of the spiral
tongue or pump, the head is a little prominent and
rounded ; and immediately below the middle of this pro-
minence there is a very minute, membranous, triangular
or semicircular piece; which from its position, as cover-
ing the base of the antlia, may be regarded as the rucU-

* Plaxj: VI. Fit. 13. a', b', c', d'.

Vol. I, p. 394—,

470 EXTERNAL ANA'l'OMY 01' INSECTS.

meat of the upper-lip (labrum) ^ On each side of the
outer base of the antlia is another small immoveable
piece, resembling a flattened tubercle, the end of v^hich
is internally hairy or scaly: these pieces appear to repre-
sent the mandibles K Near the base of each half of the
anfUa, just below a sinus, may be distinctly seen the mi-
nute, usually biarticulate rudiment of a maxillary pal-
pus ^; demonstrating to a certainty that these spiral or-
gans,' at least their lateral tubes or Solenaria, are real
maxillffi'*. The rudiment of the under-lip {Labium) is
the almost horny triangular piece united by membrane
to the two stalks of the maxilte, and supportmg at its
base the recurved labial palpi ; which are so well known
that I need not enlarge upon them ^ Amongst these
parts there seems at first sight no representative of the
tongue; but M. LatreiUe has advanced some very mge-
niotis, and I think satisfactory arguments S Avhich go to
prove that this part, at least the tongue of Hymenoptera,
has its analogue in the intermediate tube or Fistula
formed by the union of the two maxillae, and which con-
veys the fluid aliment of this Order to t\x^ pharynx. As
in Diptera the maxillcB sometimes merge in the labium,
so here the tongue (as it were divided longitudinally)
mero-es in the maxillae. He further observes, that in a
transverse section of the maxilla of the death's-head
hawk-moth {Sphinx Atropos), the lateral tube appeared

•.. Ptate VI. Fig. 13. a'. Savigny Anim. sam Vcrtcbr. I. i. 3-.
. b ihid. i. Plate VI. Fig. 13. C.

'■ Ibid. Fig. 13. h". Savigny nhi supr. o.
d Plate VI. Fig. 13. d'. Savigny tibi supr.f. 1—5. o.
e Ibid. Plate VI. Fig. 13. b'.
i Did. d'Hisl. Nal. xvii. 467.

EXTERNAL ANAT03IY OF INSECTS.

471

to be divided into two by a membranous partition, and
to contain in the upper cavity a small cylindrical tube,
which seemed to be a trachea ^. To animals that are
without lungs, and breathe by trachea;^ suction must be
performed in a very different way from what it is by
those that breathe by the month : and as in the very ex-
tended organs in question the fluid has a long space to
pass before it reaches the jphai-y7ix, in some way or other
these lateral tubes may have the power of producing a
vacuum in the middle tube, and so facilitate its passage
thither. We see, in the antlia^ that the maxilltE receive
tlieir vast elongation at the expense of all the other or-
gans, except the labial jpalpi.

iv. Rostndum ^. — An animal very annoying to us af-
fords the type of the next kind of imperfect mouth — I
mean the^m. Its oral apparatus, which I would name
rostruluin^ appears to consist of seven pieces. First are a
pair of triangular organs, the lamina^ which together
somewhat resemble the beak of a bird, and are affixed,
one on each side of the mouth, under the antennje: these
represent the mandibles of a perfect mouth <=. Next, a
pair of long sharp lancets {Scalpella\ which emerge from
the head below the laminae: these are analogous to viax-
illiE^: a pair of palpi, consisting of four joints, are at-
tached to these near their base % which of course are
maxillary palpi. And lastly, in the midst of all is a
slender setiform organ {ligula), which is the counteipart
of the tojigue ^ Rosel, and after him Latreille, seem to

« N. Diet. (CHist. Nat. iv. 253.

Pr.ATii VII. Fig. 8. c', d', e', h". Ibid. c'.

" Ibid. d'. •= Ibid. h". ' Ibid. e'.

47'2 EXTERNAL ANATOMY OF INSECTS.

have overlooked this hist piece, since they reckon only
six pieces in the flea's mouth ^ : but the hand and eye of
our friend Curtis have detected a sevetiih, as you see in
his figure. From this account it appears, that the elon-
gation of the organs of the Aphaniptera Order is at the
expense of the labkm and its palpL

V. Rostellum—^o little is known of the composition
of the next kind of imperfect mouth, that I need not en-
large upon it. It is pecidiar to the louse tribe {Pedicu-
lidcs), and it consists of the tubulet {Tuhidus), and si-
phuncle {Siphunadus). The former is slenderer in the
middle than at the base and apex, the latter being tur-
gid, rather spherical, and ai-med with claws which pro-
bably lay hold of the skin while the animal is engaged in
suction. When not used, the whole machine is with-
drawn within the head ; the siphuncle, which is the suc-
torious part, being first retracted within the tubulet, in
the same way as a snail retracts its tentacula ^. This ap-
paratus seems formed at the expense of all the other
organs.

There are some other kinds of imperfect mouth,
which, though they seem not to merit each , a distinct
denomination, should not be passed altogether without
notice. The first I siiall mention is that of the family of
Pupipara Latr. {Hippohosca L.)- It consists of a pair
of hairy coriaceous valves, which include a very slender
rigid tube or siphuncle, the instrument of suction, which
Latreille describes as formed by the union of two seti-

=- Rosel. ii. /. ui./- 15. Latreille Gen. Crusl. et Ins. iv. 365.
•> Swnmmeidam Bibl. Nal. I. ii./. 4.

EXTERNAL ANATOMY OF INSECTS. 473

form pieces* . In Melop/iagns, the sheep-louse, the luiiou
of the valves of the sheath is so short, that they appear
like a tube ; but if cut off they will separate, and show
the siphuncle, as fine as a hair, between them. This or-
gan is of a type so dissimilar, as was before observed, to
that of the Diptera in general, and approaches so near to
that of the dog-tick {Ixodes\ that they may be deemed ra-
ther apterous insects with two wings, than to belong to that
Order ; and the circumstance that some of the family are
apterous confirms this idea. In fact they are a transition
family tliat connects the two Orders, but are nearest to
the Apta-a. In Nycterihia the oral organs differ from
those of the other Pupipara in having palpi. This also
is the case with those of the genus Ixodes, the palpi of
which are placed upon the same base with the instru-
ment of suction, than which they are longer : they ap-
pear to consist of t'wo joints, the last very long and flat.
The instrument of suction itself is formed by three hard
rigid laminas ; two shorter parallel ones above, that co-
ver the third, which is longer and broader, and armed
on each side with several teeth like a saw, having their
points towards the base Many of the other Acari L.
have mandibles, and several have not : but their oral or-
gans have not yet been sufficiently examined ; and from
the extreme minuteness of most of them, this is no easy
task; nor to ascertain in what pomts they differ or
agree.

If you consider the general plan of the organs of man-
ducation in the vertebrate animals, how few are the va-

* N. Diet. d'Hist. Nat. xxviii. 266.
Ibid. xvi. 433. Dc Gcer vii. t. vi./. A. Not quite accurate.

471' EXTERNAL ANATOMY OF INSECTS.

nations that it admits ! An upper and a lower jaw
planted with teeth, or a beak consisting of an upper or
a lower mandible with a central tongue, form its princi-
pal features. But in the little world of insects, how won-
derful and infinite is the diversity which, as you see, in
this respect they exhibit ! Consider the number of the
oro-ans, the varying forms of each in the different tribes,
adjusted for nice variations in their uses :— how gradual,
too, the transition from one to another ! how one set
of instruments is adapted to prepare the food for deglu-
tition by mastication ; another merely to lacerate it, so
that its juices can be expressed ; a third to lap a fluid
ahment; a fourth to imbibe it by suction— and you will
see and acknowledge in all the hand of an almighty and
all-bountiful Creator, and glorify his wisdom, power,
and goodness, so conspicuously manifested in the struc-
ture of the meanest of his creatures. You will see also,
that all things are created after a pre-conceived plan ; in
which there is a regular and measured transition from
one form to another, not only with respect to beings them-
selves, but also to their organs— no new organ being pro-
duced without a gradual approach to it; so that scarcely
any change takes place that is violent and unexpected,
and for which the way is not prepared by intermediate
gradations. And when you further consider, that every
being, with its every organ, is exactly fitted for its func-
tions; and that every being has an ofiice assigned, upon
the due execution of which the welfare, in certain re-
spects, of this whole system depends, you will clearly
perceive that this whole plan, intire in all its parts, must
have been coeval with the Creation ; and that all the
species,-subject to those variations only that chmatc

EXTERNAL ANATOMY OF INSECTS.

475-

and diHerent food produce, — have remained essentially
the same, or they would not have answered the end for
which they were made, from that time to this.

Havmg given you this particular account of the trophi
or organs of the mouth of insects, I must now make some
observations upon the othe7- parts of the head. I have
divided it, as you see in the Table, uito face and subface;
the former including its upper and the latter its lower
surface. Strictly speaking, some parts of the face, as the
temples and cheeks, are common to both surfaces ; but
I do not therefore reckon them as belonging to the sub-
face, which, exclusive of the mouth and its organs, con-
sists only of the throat, and where there is a neck, the
giila.

i. Nasus^.—I shall consider the parts of the face in the
order in which they stand in the Table, begmning with
the 7iasiis or nose. Fabricius has denommated this part
the clypeiis, in which he has been followed by most mo-
dern Entomologists. You may therefore think, perhaps,
that I have here unnecessarily altered a term so gene-
rally adopted, and expect that I assign some sufficient
reasons for such a change. I have before hinted that
there is good ground for thinking that the sense smell
in insects resides somewhere in the vicmity of this part;
and when I come to treat of their senses, I shall produce
at large those arguments that have induced me to adopt
this opinion : and if I can make out this satisflictorily,
you will readily allow the propriety of the denomination.
I shall here only state those secondary reasons for the

Plates VJ. VII. XXVII. a.

476 EXTERNAL ANATOMY or INSECTS.

term, which, in my idea, prove that it is mucli more to
the pm-pose than clypeus. This last word was originally
applied by Linne in a metaphorical sense to the ample
covering of the head of the Scarabceidce, and the thoracic
shield of Silphciy Cassida, Lampyris, and Blatta : in all
which cases there was a propriety in the figurative use
of it, because of the resemblance of the parts so illustrated
to a shield. But when Fahricius (though he sometimes
employs the term, as Linne did, merely for illustration,)
admitted it into his orismological table, as a term to re-
present universally the anterior part of the face of insects
to which the labrum is attached (though in some cases
he designates the labrum itself by this name), it became
extremely inappropriate; since in every case, except that
of the Scarahcsida, the part has no pretension to be
called ^shield;— so tliat the term is rather calculated to
mislead than illustrate. This impropriety seems at length
to have struck M. Latreille, since in a late essay > he has
changed the name of this part to Epistomis, a term signi-
fying the part above the mouth. But there are reasons,
exclusive of those hereafter to be produced concerning
the sense of smell, which seem to me to prove th^i nastis
is a preferable term; not to mention its claun of priority,
as having been used to signify this part a century ago''.
When we come to consider tlie terms for the other parts
of the head, as lips, jaws, tongue, eyes, temples, cheeks,
forehead, &c. the concinnity, if I may so speak, and har-
mony of our technical language, seem to require that the
part analogous in point of situation to the nose of verte-

Oraaimat. Exter. dcs Ins. 196. ■ . ,

" In the Tramactions of the Royal Socicfj/, this part in Anobiim
Icsscllaium is so called, xxxiii. 159—.

EXTERNAL ANATOMY OF INSECTS. 477

brate animals should bear the same name. And any per-
son who had never examined an insect before, if asked
to point out the nose of the ammal, would immediately
cast his eye upon this part : so that one of the principal
uses of imposing names upon parts — that they might be
more readily known — would be attained. If it is object-
ed, that calling a part a nose that has not the sense of
smell, supposing it to be so, might lead to mistakes — I
would answer, that this objection is not regarded as va-
lid in other cases : for instance, the viaxillne are not ge-
nerally used as jam, and yet no one objects to the term ;
because, from their situation, they evidently have an ana-
logy to the organs whose name they bear. But enough
on this subject — we will now consider the part itself.

To enable you to distinguish the nose of insects when
it is not separated from the rest of the face by an impressed
line, you must observe that it is the terminal middle part
that sometimes overhangs the upper-lip, and at others
is nearly in the same line with it; that on each side of it
are the cheeks, which run from the anterior half of the
eyes to the base of the mandibles. Just below the an-
tennae is sometimes another part distinct from the nose,
which I shall soon have to mention ; so that the nose
must not be regarded as reaching always nearly to the
base or insertion of the antennae, smce it sometimes oc-
cupies only half the space between them and the upper-
lip, which space is marked out by an impressed line.
But you will not always be left at such uncertainty when
you want to ascertain the limits of the nose ; for it is in
many cases a distinct piece, separated by an elevated or
impressed line from the rest of the face. This separa-
tion is either partial or universal. Take any species of

478 EXTERNAL ANATOMY Ol" INSECTS.

the o-enera Copris, Onitis, or Ateuchus, and you will see
the nose marked out in the centre of the anterior part of
the tace by two elevated lines, forming nearly a triangle
and bounded by the horn \ Or take a common wasp or
hornet, and you will find a similar space, though ap-
proaching to a quadrangular figure, marked out by im-
vressed lines ^ In Bhagio and Sciara, two Dipterous ge-
nera, this impression is so deep as to look like a suture
Between these lines, in those cases, is included what 1
call the nose. As to substance, in general it does not dif-
fer from the rest of the head; but m the Clendce it is
almost membranous. You must observe, that m all these,
what at first sight appears to be the termination of the
front, is not the nose, but the narrow depressed piece
that intervenes between it and the lip. With regard to
its clothing, it is most commonly naked, but m some ge-
nera it is covered with hair; in Crabro F. often with
golden or silver pile, which imparts a singular brilliance
to the mouth of the insects of that genus: M. Latreille
supposes that the brilliant colours of the golden-wasp
iCj'ysis L.) may dazzle their enemies, and so promote
their escape c ; the brilliance of the mouth of the Cr.-
bro may on the contrary at first dazzle their prey for a
moment, so as ioprevent their escape. The form of the
nose, where distinct fi-om the rest of the face, admits of
several variations: thus in the Staph^Unidce and Clend^
it is transverse and linear; in Cop-is it is triangiilar with
the vertex of the triangle truncated; in Vespa Crabro it
is subquadrate and sinuated. In many Heteromerous

a XXVII. F:a. 4. a. "

c oZ-v. Nora, .snr les Hy^ncnopicres {Ann. du Mus.) 5.

KXTKHNAL ANATOMY OF INSECTS. 4.79

beetles ' it is rounded posteriorly : in Felecotma, a new
genus in tliis tribe, related to Asida, there is a deep an-r
terior sinus ; in Blaps the anterior margin is concave ;
in Cetonia^ Bwwnii, and atropunctata (forming a distinct
subgenus), it is bifid: it varies in the Scarabceida^ in
some being bidentate, in others quadridentate, and in
others again sexdentate, including the cheeks : in Myla-
bris^ a kind of blister-beetle, it is transverse and neai-ly
oval ; in Laviia, a capricorn-beetle, it represents a paral -
lelogram; and in most Orthoptera it is' orbicular : in Tet-^
tigonia F. it is prominent, transversely furrowed, and di-
vided by a longitudinal channel : in Otiocenis K. it pre-
sents the longitudinal section of a cone <=: in the Diptera
Order, with the exception of the Tipulidce and some
others, in which it unites with the cheeks, &c. to form a
rostrum, the nose in general, as to form, answers to its
name, resembling that of many of the Mammalia: iii
some of the Asilidcc it is very tumid at the end, and ter-
minates m a sinus, to permit the passage of the proboscis
to and fro : in many of the Sijrphida;, &c. it is first flat
and depressed, and then is suddenly elevated, so as to
give the animal's head the air of that of a monkey : in
some tribes, as Rhingia, Nemotelus, Ertstalis, &c., in
conjunction with the cheeks it forms a conical rostrum :
ill Tabanus bovmus, and other horse-flies, it tenninates
in three angles or teeth. Many more forms might be
mentioned, but these will suffice to give you a general
idea of them. In size and proportiotis the nose also va-

" Those beetles whose posterior pair of tarsi liave only /o/»- joints,
and the two anterior ^ve, are so called.

Kirby in Linn. Trans, xii. 464. /. xxiii./. 6,
^ Ibid, xiii.i.i./. 1.6.

480 EXTERNAL ANATOMY OF INSECTS.

ries. It is frequently, as in Tettigonia, the most conspi-
cuous part of the face, both for size and characters; but
in the StaphT/linida it is very small, and often scarcely
discernible, being overshadowed by its ample fr6nt: and
it may be observed in general, that when the antennae
approximate the mouth, as in this genus and many others,
the front becomes ample, and the nose is reduced to its
minimuin : but when they are distant from the mouth, the
reverse takes place; and the nose is at its maxirnwn and
the front at its minimim. Mutilla, Myrmecodes, Scolia, &c.
in the Hxjmenoptera, are an example of the former; and
the Pompilidce, Spheeida, VespidcB, &c. of the latter. In
Myopa huccata, &c. its length exceeds its width ; but more
commonly the reverse takes place. The circumseriphon
the nose also deserves attention. It is usually termmated
behind by the front {frons\ or, where it exists, by the^^os^
nasus, in the sides by the cheeks, and anteriorly by the la-
hnm. But this is not invariably the case; for m the Cmi-
cid^, in which the cheeks form the bed of the Prommas,
the front embraces it on each side by means of two lateral
processes, that sometimes meet or lap over each other
anteriorly, which gives the nose the appearance of bemg
insulated ; but it really dips below these lobes to jom the
labrum. This structure you may see m Edessa F., and
many other bugs. This part sometimes has its arms.
Thus in Copm, and many Dynastidce, the horns of the
head seem, in part at least, to belong to this portion of
if in Tipida oleracea (the crane-fly), &c. it termmates
before in a horizontal mucro. In Osmia cornuta, a kmd
of wild-bee, each side of the nose is armed with a ver-
tical horn. The margin of the nose in most Lamelhcora
insects, though mostly level, curves upwards.

EXTERNAL ANATOMY OP INSECTS. 481

I am next to mention a part of the nose which me-
rits a distinct name and notice, which I conceive in some
sort to be analogous to the nostrils of quadrupeds, and
which I have therefore named the Rhinarium or nostril-
piece. I had originally distinguished it by the plural term
7iares, nostrils; but as it is usually a single piece, I thought
It best to denote it by one in the singular. When I
treat of the senses ©f insects, I shall give you my reasons,
as I have before said, for considering this part as the
organ of scent, or connected with it, which you will then
be able to appreciate. I shall only here observe, that the
piece in question is in the usual situation of the nostrils
—between the nose and the lip. In a large number of
insects this part may be regarded as nearly obsolete;
or at least it is merely represented by the very narrow
membranous line that intervenes between the nose and
the lip and connects them; which, as in the case of the
head oi Harpali before noticed, may be capable of ten-
sion and relaxation, and so present a greater sm-face to
the action of the atmosphere. But I offer this as mere
conjecture. In the lady-bird {Coccinella) this line is a
little wider, and becomes a distinct Bhinarium; as it
does also in Geotrupes. With respect to its msei'tio7i,
the rhinarium is a piece that either entirely separates
the nose from the lip, or only partially : the former is
the most conmion structure. It is particularly remark-
able in a New Holland genus of chafers {Anoplognathus
Leach). In A. viridiceneus it is very ample, and forms
the under side of the recurved nose, so that a large space
intervenes between the margin of the latter and the base
of the labnm. In Macrojms Thunb., of the Capricorn
tribe {Cerambyx L.), the nostril-piece, which forms a

VOL. III. 2 I

482 EXTERNAL ANATOMY OF INSECTS.

distinct segment, is narrower than the nose, and the
upper-lip than the nostril-piece, forming as it were a
triple gradation from the front to the mouth. Again, m
others the part in question is received mto a sinus of the
nose. This is the case with the dragon-flies {Libelluhna),
in which this sinus is very wide; in the burying-beetle
(Necrophorus) % in some species of which it is deep but
narrow ; and in a species of Tenebrio from New Holland,
which perhaps would make a subgenus. If you examme
with a common glass any of the larger rove-beetles (S^a-
phylinid^), you will find that the nose itself seems lost m
the nostril-piece, both together forming a very narrow
line across the head above the labrum, without any ap-
parent distinction between them ; but if you have recourse
to a higher magnifier, you will find this divided mto an
upper and lower part, the former of the hard substance
of the rest of the head, and the latter membranous. 1
once was of opinion that the prominent transversely fiir-
rowed part, so conspicuous in the face of Tettigoma F. ,
was the front: but upon considering the situation of this,
chiefly below the eyes and antennas, and comparmg it
with the analogous piece in Fulgora laternaria and other
insects of the Homopterous section of theHemrptera I
incHne to think that it represents the nose, and that the
longitudinal ridge below it is the nostril-piece ^. In the
Heteropterous section it is merely the vertical termina-
tion of their narrow nose. In odier insects agam, this
part approaches in some measure to the common idea of
nostrils; there being t.o, either one on each sule the
nose, or two approximated ones. If you catch the fii
humble-bee that you see busy upon a flower, you will
^.p..TKVT.Fia.l0.g'. ••Ibid.Fio.T.a. ' § '

KXTEUNAL ANATOMY OF INSECTS. 483

discover a minute membranous protuberance under each
angle of the nose. Something similar may be observed
in some species of Asilus L. In the Orthoptera^ espe-
cially in Blatta, Phasina, and some Locustce, twfo roundish
or square pieces, close to each other on the lower part
of the nose, represent the nostrils — With regard to
substance, in the chafer-tribes, at least those that feed
on leaves or living vegetable matter, as the Melolon-
tJiid(E, Anoplognathidce, and in many other insects, the
rhinarium is of the same substance with the rest of the
head; but in Mao'opus Thunb., Staphylinus, Nccrophotiis,
&c., it consists of membrane.

ii. Postnasus ^. — This is a part that appears to have
been confounded by Entomologists widi the front of in-
sects; in general, indeed, it maybe regarded as included
m the nose, and does not require separate notice : but
there are many cases in which it is distinctly marked out
and set by itself, and in which it forms a useful diaoiio-
stic of genera or subgenera. There is a very splendid
and beautiful Chinese beede, to be seen in most collec-
tions of foreign insects {Sagra purpurea), in which this
part forms a strildng feature, and helps to distuiguish the
genus from its near neighbour Donacia. If you examine
its face, you will discover a triangular piece, below the
antennae and above the nasus, separated from the latter
and fi'om the front by a deeply-impressed Ime : this is the
postnasus or after-nose. Again : if you examine any spe-
cunens of a Hymenopterous genus called by Fabricius
Prosopis {Hylaus Latr.), remarkable for its scent of
baum, you will find a similar triangle marked out in a

" Plate VI. Fig. 4. g'. b p,.^,^j,, vi.VII, b.

2 I 2

4.8'i EXTERNAL ANATOMY OF INSECTS.

similar situation \ In many Coleopterous insects, besides
Sagra, you will discover traces of the part we are consi-
dering : as in Anthia, Dytiscus, and several others of the
Predaceous beetles. In Cistela it is larger than the nose
itself; but it is more conspicuous in the Orthoptera, par-
ticularly in Locusta {Gtyllus F.), in which it is the space
below the antennae, distinguished by two or four rather
diverging ridges ^ In the Lihellulina, Myrmeleonina,
&c. it is a distinct transverse piece. In Dasyga Latr.,
a kind of bee, it is armed with a transverse ridge or horn
—But enough has been said to render you acquainted
with it ; I shall therefore proceed to the next piece.

iii. Frons The Front of insects may be denomi-
nated the middle part of the face between the eyes,
bounded anteriorly by the nose, or after-nose, where it
-exists, and the cheeks ; laterally by the eyes; and poste-
riorly by the vertex. Speaking properly, it is the region
of the anten7ics; though when these organs are placed
before the eyes, under the margin of the nose, as in many
^ Lamellicorn and Heteromerous beedes, they seem to be
rather 7iasal i\i^n frontal. This part is often elevated,
as in the elastic beetles {Elater\ whose faculty of jump-
ino- by means of a pectoral spring, has been related to
you ^, In Anthia, a Predaceous beetle, it has often three
longitudinal ridges. In many of the Capricorn beetles
^Ceramhyx L.), it is nearly in the shape of a Calvary
cross, with the arms forming an obtuse angle, and then
terminating at the sinus of the eyes in an elevation for
the site of the antennae. In the ants also {Formicidcv),

- Kirby Mon. Ap. Angl. i. t. i. Mclitta. *. b./. 3.

u PtATE VI. Fig. 4. b. ' P^-^tes VI. VII. c

J Vol. II. p. ;517— .

EXTERNAL ANATOMY OF INSECTS. 4-85

the front is often elevated between those organs. In
Ponera, one tribe of thern, this elevation is bilobed,
and receives between its lobes the vertex of the post-
nasus. In the hornet {Vespa Crabro) the elevation is a
triangle, with its vertex towards the mouth. In Sagra
It is marked out into three triangles, the postnasus mak-
ing a fourth, with the vertexes meeting in the centre.
In the Dynastida and Scarabceidce the horns are often
frontal appendages, as is that of Evipusa Latr., a leaf-
insect, and probably those of SpJiinx latrophceV., which
affords a singular instance of a horned Lepidopterous one.
Sometimes it is an ample space, reducing the nose to a
very narrow line, as in the Staphylinidce, or sending
forth a lobe on each side, as before mentioned, which
embraces the nose. In a species of bug from Brazil, re-
lated to Avadm F., these lobes are dilated, foliaceous,
and meet before the nose, so as to form a remarkable
extended frontlet to the head. In others this part is ex-
tremely minute : thus in many male flies and other in-
sects, as the Libelhdina, whei'e the eyes touch each other,
the front is cut off from the vertex and reduced to a small
angle. In the female flies the communication with the ver-
tex is kept open, and the front consequently longer. In
the horse-flies (Tabanida), in Hcematopota, and Hepta-
ioma, the frontal space is wider than in the rest of that
tribe. Many of these are distinguished by a levigated
area behind the antennae in the part we are treating of.
In the LibelluUna, and in the drone-bee, whose eyes are
confluent, the stemmata are in the front. In many Or-
thoptera also, as Lociista Leach, one of them is below
the antennas; and in the lanthorn-fly tribe {Fidgoridce\
both these organs, which are situate between them and

486 EXTERNAL ANATOMY OF INSECTS.

the eyes, as they do also in Truxalis, appear to be in
it^ In this tribe the rostrum is an elongation of the
part in question; and perhaps you would think at first
that what I have considered as the nose in Tettigonia F.
was also a tendency to this kind of rostrum ; but if you
examine the great lanthorn-fly {Fulgora laternaria), you
will find besides, at the lower base of the lanthorn, a tri-
angular piece analogous to the nose of Tettigonia, and
befow it another representing its nostril-piece :— the hori-
zontal part of the nose in that genus may perhaps be re-
garded as part of the front. In Truxalis F. the face
consists of a supine and prone surface, and the latter is
composed of the front, after-nose, nose, and organs of the
mouth. I may notice here a most remarkable and singu-
lar tribe of bugs, of which two species have been figured
byStolP: in these the head, or rather those parts of it that
we have now been describing, the nose, namely, the after-
nose, and front, are absolutely divided longitudinally m
two, each half having an eye and antenna planted m it;
or perhaps, as it is stated to be divided in one mstance to
the commencement oi' the promuscis, the nose is left m-
tire, and dips down, as in cases before alluded to : so that
in this the nose appears to leave the lobes of the fi'ont,
which in others embrace its sides.

iv. Vertex'.— We now come to the vertex, or crown
of the head ; which is situated behind the fi'ont, and,
except where the communication is intercepted by con-
fluent eyes, adjoins it. It is laterally bounded by the
hind part of the eyes and the temples; ^nd posteriorly/,

Plate XXVI. Fig. 41. i.
1' StoU Punaises, I. xxxix. /. 279, 280.
' Plates VI. VII. XXVI. d.

EXTERNAL ANATOMY OF INSECTS. 487

where that part exists, by the occiput. The vertex may
be denominated the ordinary region of the stemmata :
for though in several cases, as we have just seen, one or
more of them are planted in the front; yet this in the great
majority, especially in the Hymenoptera, is their natural
station. In Blatta and some other Orthoptera the poste-
rior angle of the head is the vertex. In many dung-
chafers of Latreille's genus Onthophagus, which are said
to have occipital horns, as O. nutans^ nuchico)-nis, Xi-
phias, &c., the horn really arms the part I regard as the
vertex. In Loaista Leach, this part is very ample, and
in Truxalis very long ; but more generally it is small,
and not requiring particular notice.

V. Occiput^. — The, occiput^ ox hind-head, is that part
of the face that either forms an angle with the vertex
posteriorly, or slopes downwards from it. It has for its
lateral boundaries the temples, and behind it is either
terminated by the orifice of the head, or in many cases
by the neck. In those beetles that have no neck, as the
Lamellicorn and Capricorn, the hmd-head is merely a de-
clivity from the vertex, usually concealed by the shield of
the thorax, very lubricous, to facilitate its motion in the
cavity of that part, and at its posterior margm distin-
guished by one or two notches, which I shall notice
hereafter, for the attachment of the levator muscles : but
in those beetles or other insects that have a neck, or a
versatile head, the occiput forms an angle with the vertex,
often rounded, and sometimes acute. This structure may
be seen in Latreille's Trachelides, and several other bee-
tles. In the Hymenoptera, Diptera, and others with a

" Plates VI. VII. e

4-88 EXTERNAL ANATOMY OF INSECTS.

versatile head, the part now under consideration curves
inwards from the vertical line, so as with the temples and
under parts of the head to form a concavity adapted to
its movement upon the trunk.

vi. Ge7i£E ^. — The cheeks of insects {Gence) usually sur-
round the anterior part of the eyes, and lie between them
and the mandibles or their representatives. Where they
approach the latter, as in the Predaceous beetles {Cicin-
dela, Carahus L. &c.), they are very short, and of course
longer where the eyes are further removed from the
mouth; as in the Rhyncophorous beetles {Curculio L,.),
where they form the sides of the rostrum, and often con-
tain a channel which receives the first joint of the anten-
nse, when they are unemployed. In the Scarabceida and
many other Lamellicorn beetles, their separation on each
side from the nose is marked by a ridge ^; and in the
wasps ( Vespa) by an impressed line or channel. In an
African tribe at present arranged with Cetonia F., to
which a hicoriiis Latr.= and another, which he has named,
I believe, C. vitticollis, belong, the cheeks are porrected
on each side of the mouth into a horizontal horn. These
horns have at first the aspect of a pair of open mandibles.
In the magnificent Goliathi Lam., the horns of the male
are rather a process of the cheek than of the nose. In
Ahtrnus, Hispa, and other beetles, these parts, by their
elevation and conjunction with the lower side of the
head, form a kind of fence which surrounds and protects
the oral organs; in many Cimicidce, by a similar eleva-
tion of the cheeks, the bed of the promuscis is formed.

" Platks VI. VII. f. " Pt-AXF, XXVII. Fig. 4. f.

Cuv. Rcgnc Animal, iii. /• xiii./. 4.

EXTERNAL ANATOMY OF INSECTS.

489

In the Homopterous Hemiptera they run parallel nearly
with the rhinarium or nostril-piece. In the Hymenopta-a
they are almost always ample, but they are confined to
the lower side of the eye. In 8irex Gigas, and others of
that genus, the cheek at the base of the mandible is di-
lated so as to form a rounded tooth below it In the
Capricorn-beedes it is considerable, and sometimes ter-
minates, at the base of the mandible, in two or three
notches. In Scaurus and Eutychora, darkling-beetles,
the cheek below projects into a lobe that covers the base
of the maxilla. But the animal distinguished by the
most remarkable cheeks is a species of Phyganea L.
{Phyganea peisonata Spence) ; for from this part pro-
jects a spoon-shaped process, which curves upwards, and
uniting with that of the other cheek, forms an ample mask
before the face, the anterior and upper margin of which,
in the insect's natural state, are closely united ; and the
posterior part being applied to the anterior part of the
eye, causes the face to appear much swoln. It looks as
if it was a single piece ; but upon pressing the thorax it
opens, both above and in front, into two parts, each con-
vex without and hollow within, and each having attached
to its inside a yellow tuft of hair resembling a feather.
The use of this machinery at present remains a my-
stery ^.

vii. Temjwra •'.—The temples ( Tonpora) are merely
a contmuation of the cheeks to the posterior limit of the

" This insect was taken both at Matlock and Exmouth. The body
and thighs are of a light-brown, wings testaceous, legs pale ; antenna
between setaceous and filiform, two-thirds the length of the body •
first joint not much thicker than the rest.

" PLATJiS VI. VII. g.

4-90 EXTERNAL ANATOMY OF INSECTS.

head, forming its sides and posterior angles, and includ-
ing the hinder part of the eyes, the vertex, and the occi-
put. They seldom exhibit any tangible character, ex-
cept in certain ants {Atta Latr.), in which their angle
terminates in one or two strong spmes, giving the ani-
mal a most ferocious aspect; and in that remarkable ge-
nus Coi-ydalis they are armed below with a tooth or point,
which was not overlooked by De Geer ^

viii. Oculi ^— I must now call your attention to organs
of more importance and interest, and which indeed in-
clude a world of wonders: I mean the eyes {Oculi) of
insects. These differ widely from those of vertebrate
animals, bemg incapable of motion. They may be re-
garded as of three descriptions— smpZ^, conglomerate,
and compound.

1. Simple Eyes We will consider them as to their
number, stnicture, shape, colour, magnitude, situation, and
arrangement.

As to their number, they vary from two to sixteen.
In the flea, the louse, the harvest-man {Phalangium),
there are only a pair ; in the bird-louse of the goose
(mrmus Anseris), and probably in others of the saine
crenus, there are>.r^ ; in some spiders {Sajtodes, Dys-
dera, and Segestria Latr.^), and some scorpions % there
are«^. In the majority of spiders and ^.^^i^^n^ra

a De Geer iii. 561. t. xxvii./. 1. ^ P-xes VI. VII. XXVI. h.

c Plate VII. Fig. 8, 9. XXVI. Fig. 43. h.

a Viz. one on each side above, and one below.

o Walckenaer Arancidcs, t. v./. 60, 52. t. viu./. 82.

. ~s(...™^
^ ^::^^eo. tbe head, .here the, are lar,e.
but not conspicuous, at least in my specimen.

EXTERNAL ANATOMY OF INSECTS.

491

sitans, Scorpio maurus, &c. there are eight and in Po-
dura and Sminthurus Latr. there are sixteen

As to their structure, nothing seems to have been ascer-
tained ; probably their organization does not materially
differ from that of one of the lenses of a compoimd eye ;
which I shall soon explain to you.

Their colour in the many is black and shining, but in
the bird-louse of the goose they are quite white and
transparent. In spiders they are often of a sapphirine
colour, and clear as crystal. In Scolopendra morsitans
and many spiders, scorpions, and phalangia they ap-
pear to consist of iris and pupil, which gives them a
fierce glare, the centre of the eye being dark and the
circumference paler. In the celebrated Tarantula {Ly-
cosa Tarantula), the pupil is transparent, and red as a
ruby ; and the iris more opaque, paler, and nearly the
colour of amber.

Where there are more than two, they vary in magni-
tude. In the enormous bird-spider {Mygale avicularia)
the four external eyes are larger than the four internals-
but in the Tarantula and Sphasus, the two or four inter-
nal are the largest. In Clubiona and Ih-assus they are all
nearly of the same size'*; and in the Micrommata family
they are very small

They vary also in shape. In Scolopendra morsitans the
three anterior ones are round, and the posterior one
transverse, and somewhat triangidar. In Mygale cal-
peiana, a spider, the two smallest are round and the rest

DeGeervii. t. iii. /. 8,9, 12.
" Plate XXVI. Fig. 43. h. c Walck. Aran, t, i.f. 3

" ^^'f'- V./. 42_4a. e Ibid. /..iv./. 41.

4-92 EXTERNAL ANATOMY OF INSECTS.

oval ^ In the trapdoor or mason spider {Mygale ca-
mentaria), the four small internal ones are romid, and
the large external ones ovaP ; and those that are cir-
cumscribed posteriorly with an impressed semicircle, are
shaped like the moon when gibbous ^

The situation and arrangement of simple eyes are also
various. In many they are imbedded, as usual, in the
head; but in the little scarlet mite, formerly noticed",
{Tromhidiu7n holosericeum), they stand upon a small foot-
stalk ^: the hairiness of this animal might otherwise have
impeded its sight. In spiders they are planted on the
back of the part that represents the head, sometimes four
on a central elevation or tubercle, and the remainmg
four below it— as in Lycosa; sometimes the whole eight
are on a tubercle, as in Mygale; and sometimes, as in
the common garden-spider {Epeira Diadema), upon
three tubercles, four on the central one and two on each
of the lateral ones. Other variations in this respect might
be named in this tribe. In the scorpions a pair are placed
one on each side, on a dorsal tubercle, and the other four
or six on two lateral ones of the anterior part of the
head ' In the Phalangida^ the frontal eyes of the scor-
pion cease, and only a pair of dorsal ones are inserted
vertically in the sides of a horn or tubercle, either bihd
or simple, often itself standing upon an elevation which
emerc.es from the back of the, animal^. If their eyes
were not in a vertical and elevated position, tlie sight ot

. Walck.^mn./.i./.2. 1' v f I'-^s/s

r, - , X •• /• 1ft on Vol. I. p.

e DeGeervu.138. ^.viii./. 15.^i/. ' Ibid.i. xl./. 3. oo, j/^.
E Plate XXVI. Fig. 43. h.

EXTERNAL ANATOMY OF INSECTS.

49S

these insects would be very limited ; but by means of the
structure just stated, they get a considerable range of sur-
rounding objects, as well as of those above them. With
regard to the arrangement of the eyes we are consider-
ing, it varies much. Sometimes they are placed nearly
in the segment of a circle, as in those spiders that have
six eyes only, before noticed sometimes in two straight
lines''; at others in two segments of a circle at others,
in three lines ^, and at others in four ^. Again, in some
uistances they form a cross, or two triangles in othei-s,
two squares ^ ; m others, a smaller square included in a
large one"; in others, a posterior square and two anterior
triangles '; sometimes a square and tjvo Imes. Though
generally separate from each other, in several cases two
of the eyes touch "; and in one instance three coalesce
into a triangle But it would be endless to mention all
the variations, as to arrangement, m the eyes of spi-
ders.

2. Conglomerate Eyes differ in nothing from simple
eyes, except that instead of being dispersed they are col-
lected into a body, so as at first sight to exhibit the ap-
pearance of a compound eye : — they are, however, not
hexagonal, and are generally convex. They occur in

Segestria perfida, Walck. Aran. t. v.f. 52. &c.
^ Tetragnatka and Latrodectes, Ibid. t. vii.f. 64. and t. ix.f. 84.
*= Ni^ssu^ coloripes. Ibid. t. vi.f. 58.

Boloineda, Ibid. t. n.f. 18, 20.
° Spkasus, Ibid. t. iii./. 24.
^ Mygale avicidaria. Ibid. t. i.f. 3.

Sparasus, Ibid. ^. iv. /. 41. Plate XXVI, Fig. 37.
" Eresus, Ibid. t. iii./ 26. ' Storena, Ibid. t. ix.f. 86

Argyroneta, Ibid.f. 88. ' Pholctis, Ibid. t. viii. f 80

"•PLATEXnr.FiG.il.

494) EXTERNAL ANATOMY OF INSECTS.

Lepisma, the lulidce, and several of the Scolopendrida.
In Scolopendraforjicata the eye consists of about twenty
contiguous, circular, pellucid lense's, arranged m five
lines, with another larger behind them, as a sentinel or
scout, placed at some little distance from the main body.
In the common millepede {lulus terrestris) there are
twenty-eight of these eyes, placed in seven rows, and
forming a triangle, thus J. —the posterior row con-
taining seven lenses, the next six, and so on, gradually
losing^ one, till the last terminates in unity. Each of
these lenses is umbilicated, or marked with a central de-
pression. In Craspedosoma Leach, you will find a similar
formation. In Glomeris zonata, a kind of wood-louse
that rolls itself into a ball, the lenses are arranged in a
line curved at the lower end, with a single one by itself
' at the posterior end on the outside ; they are oblong and
set transversely, and their white hue and transparency
give them the appearance of so many minute gems, espe-
cially as contrasted with the black colour of the annuals
Between these eyes and the antennae is another trans-
verse linear white body, but opaque, seemingly set m a
socket, and surrounded by a white elevated line, lU^e the
bezel of a ring. Whether it is an eye, or what organ, 1
cannot conjecture \ Its aspect is that of a spiracle.

3. Compound Eyes-. -These are the most common kmd
of eye in hexapod insects, when arrived at their perfect
state; in their larva state, as we have seen, their eyes
being usually simple except, indeed, those whose me-
tamorphosis is semicomplete, which have compound eyes

PLATKXXIX.FiG.ll.h. " Ibid.^.

c Pr.ATF. XTIl. Fig. 10. bee above, p. H/-

EXTERNAL ANATOMY OF INSECTS.

495

in every state. — In considering compoiuid eyes, I shall
advert to their structure, mimber, situation, Jigure, cloth-
ing, colour, and size.

As to their structure, — when seen under the microscope
they appear to consist usually of an infinite number of con-
vex hexagonal pieces. If you examine with a good glass
the eye of any fly, you will find it traversed by numberless
parallel Hnes, with others equally numerous cutting them
at right angles, so as apparently to form myriads of little
squares, with each a lens of the above figure set in it. The
same structure, though often not so easily seen, obtains in
the eyes of Coleoptera and other insects. When the eye
is separated and made clean, these hexagons are as clear
as crystal. Reaumur fitted one eye to a lens, and could
see through it well, but objects were greatly multiphed*.
In Coleoptei'ous insects they are of a hard and horny
substance ; but in Diptera, &c. more soft and membra-
nous. The number of lenses in an eye varies in different
insects. Hooke computed those in the eye of a horse-
fly to amount to nearly 7,000''; Leeuwenhoeck found
more than 12,000 in that of a dragon-fly and 17,325
have been counted in that of a butterfly ^. But of all in-
sects they seem to be most numerous in the beetles of
Mr. W. S. MacLeay's genus Dynastes. In the eyes of
these the lenses are so small as not to be easily discover-
able even under a pocket microscope, except the eye has
turned white «=: it is not, therefore, wonderful, that Fabri-

=> Reaum. iv. 245. i. Microgr. 176.

' -E/jwi. Mai-. 6. 1717. •> Am(en. Academ. vii. 141.

I possess a specimen in which the eye is partly black and partly
white: the lenses are invisible in t\\e black part, but very visible in
the white.

496 EXTERNAL ANATOMY OF INSECTS.

cius should call these eyes simple ^ In some msects, how-
ever, as in the Strepsipera Kirby, the lenses are not nu-
merous : in Xenos they do not exceed fifty, and are di-
stinctly visible to the naked eye ^ These lenses vary in
maonitude, not only in diiferent, but sometimes in the
same eyes. This is the case in those of male horse-flies
and flies, those of the upper part of the eye being much
larger than those of the lower The partitions that
separate the lenses, or rather bezels, in which they are set,
are very visible in tlie eyes just mentioned, and those of
Xenos : but in many insects they are only discernible at
the intersecting lines of separation between the lenses.
In hairy eyes, such as those of the hive-bee, the hairs
emerge from these septa. Every single lens of a com-
pound eye may be considered as a cornea, or a crystal-
line humour, it being convex without and concave within,
but thicker in the middle than at the margin: it is the
only transparent part to be found in these most remark-
able eyes. Immediately under the cornea is an opaque
varnish, varying according to the species, which pro-
duces sometimes in one and the same eye spots or bands
of diflFerent colours. These spots and bands form a di-
stinguishing ornament of many of the Tahani and other
flies! And to this varnish the lace-winged flies {Heme-
roUus, &c.) are indebted for the beautiful metallic hues
that often adorn them. When insects are dead, this
varnish frequently loses its colour, and the eye turns
white • hence many species are described as having Mc
eyes which when alive had black ones. The consistence

•a PhUos. Entomolog. 19. _ ' P^^"- ^XVI. Fig. 38.
«: Hooke Microgr. schem. xxiv.

EXTERNAL ANATOMY OF INSECTS.

497

of this covering is the same with that of the varnish of
the choroid in the eyes of vertebrate animals ; but it en-
tirely covers the underside of the lens, without leaving
any passage for the light. Below this varnish there are
numbers of short white hexagonal prisms ^, every one of
which enters the concavity of one of the lenses of the
cornea, and is only separated from it by the varnish just
described : this may be considered as the vetbia of the
lens to which it is attached ; but at present it has not been
clearly explamed how the light can act upon a retina of
this description through an opacjue varnish. Below this
multitude of threads (for such the bodies appear), per-
pendicular to the cornea, is a membrane which serves
them all for a base, and which consequently is nearly pa-
rallel with that part. It is very thm, of a black colour,
not produced by a varnish ; and in it may be seen very
fine white trachece, which send forth branches still finer,
that penetrate between the prisms of the cornea : this
membrane may be called the choroid. Behind this is a
thin expansion of the optic nerve, which is a true nerv-
ous membrane, precisely similar to the retina of red-
blooded animals. It appears that the white pyramidal
threads which form the retina of each lens are sent forth
by this general retina, and pierce the choroid by a num-
ber of almost imperceptible holes ^ From this descrip-
tion it appears that the eyes of insects have nothing cor-
responding with the icvea or humours of those of verte-
brate animals, but are of a type pecuHar to themselves.
Having explained to you the wonderful and complex

" Plate XXIII. Fig. 3.
Cuvier Anat. Compar. ii. 442-. Compare Swammerdam Bibl.
^fd /. XX./. 45.

Vol, III. 2 k.

498 EXTERNAL ANATOMY OF INSECTS.

Structure with which it has pleased the Creator to di-
stinguish the organs of vision of these minute beings,
proving, what I have so often asserted, that when ani-
mals seem approaching to nonentity, where one would
expect them to be most simple, we find them in many
cases most complex, I shall now call your attention to the
next thing I am to consider— the number of the eyes in
question. Most insects have only ifwo; but there are se-
veral exceptions to this rule. Those that have occasion
to see both above and below the head, the eyes of all
being immovable, must have them so placed as to enable
them to do this. This end is accompHshed in many
beetles, for instance Scarabaus L., Helaus Latr., &c., by
having these organs fixed in the side of the head, so that
part looks upward and part downward ; but in others
four are given for this purpose. If you examine the
common whirlwig {GyrinusNatator) that I have so often
mentioned S which has occasion, at the same time, to
observe objects in the air and in the water, you will find
it is gifted with this number of eyes. Lamia Tornator
[Cerambyx tetrophthalmus Forst.) and some others, of
which I make a genus, under the appellation of Te-
trops, are also so distinguished. In these insects, one
eye is above and the other below the base of the anten-
nae; in fact, in these the cantJms, instead of dividing die
eye partially, as in the other Capricorn-beedes, runs quite
through it at considerable width In Ryssonotus Mac-

Vol. II. p. 4, 364, &c.
b Pi ATE XXVI Fig. 36. h. Fabriciiis, and after him Olivier,
though both quote Forster, regard one of these eyes in Lamm Tor-
nator a spot; but they could not have exammed it attentively.
Saperda prceusta F. has also four eyes.

EXTERNAL ANATOMY OF INSECTS.

4-99

Leay [lAicanus nehulosus K.) the eye appears also to be
divided in two by the canthus. In the Neuroptera Order
there is more than one instance of the same kind. In
Ascalaphus there are two considerable eyes on each side
of the head, which, though clearly distinct, meet like
those of many male flies and the drone. The male, like-
wise, of more than one species of Ephemera, besides the
common lateral eyes and the stemmata on the back of
the head, have a pair of compound eyes on the top of a
short columnar process ^. In the Hemiptera Order, also,
an instance occurs of four eyes in the genus Aleyrodes ^.
Amongst the vertebrate animals, there is an example of
eyes with two pupils in AnaUeps, a genus of fishes but
no vertebrate animal has four of these organs. That
many insects should have more than two eyes, will not
seem .to you so extraordinary as that any should be found
that, like the Cyclops of old, have only one. There is,
however, an insect, before celebrated for its agility''
{Machilis polypoda Latr.), which has a single eye in its
forehead; or we may say, its eyes are confluent, without
any line of distinction between them except a small notch
behind. Now that I am treating of the number of eyes,
I must not forget to ol)serve to you, that in some insects
no eyes at all have been discovered. In Polydesmus com-
planatus, on each side of the head there is an eye-shaped
portion separated by a suture, in which under a power-
ful lens I cannot satisfy myself that I can discern any
thing like the facets that usually distinguish compound
eyes. In Geophilus electricus, another myriapod, they

^ Plate XXVI. Fig. 39. h.

" Latreille Gen. Crust, et Ins. iii. 73. N. Diet. (PHist. Nat. i. 479
•» Vol. ir. ,320.

2 K 2

500 EXTERNAL ANATOMY OF INSECTS.

certainly do not exist ^ Whence we may conclude, as
was before observed ^, that the faculty of emitting light
is rather given it as a means of defence than to guide it
in its path.

The situation of compound eyes differs in different
tribes. In some, as in the Staphylinidce, they are planted
laterally in the anterior part of the head ; in others, the
Carabi &c., in the middle; in others again, Locusta
Leach &c., in the posterior part. In some, their station
is more in the upper surface, either before or behind ; so
that a very narrow space separates them, or perhaps none
at all. Instances of this position of the eyes occur in a
minute weevil {Ramphus Clsiirv.''), and many Diptera,
&c. Of those that form an union on the top of the head,
some are placed obliquely, so as to leave a diverging
space below them, as in many Libelhdina^, the drone %
&c. Others, as Atractocerus, in which the eyes occupy
nearly the whole head, and unite anteriorly, have this
diverging space above their conflux. In Rhina barbiro-
stris Latr., another kind of weevil, they are confluent
below the head, at the base of the rostrum, and a very
narrow interval separates them above. In a large num-
ber of the Heteromerous beetles, they are set tra?isverselj/,
in the Capricorn ones longitudinally. Their surface,
when they are lateral, has usually two aspects, oneprone
to see below, the other supine to see above. In general
the eyes are situated behind the antennae, so that their
position, whether it shall be anterior or posterior, de-
pends upon that of those organs. Often, indeed, as in

- De Geer vii. 562. " Vol. II. p. 228.

« FM. Helvct. i. t. xii. *' Plate VI. Fig. 1 0.

• Kirby Man. Ajj. Angl. i. t. xi. Ajns. **• e. 1./. 2.

EXTERNAL ANATOMY OF INSECTS. 501

the last-named beetles, part of the eye is behind and part
before the antennae ; but except where there are fmir
eyes, as in Tetrops, they are never placed before or below
them.

Though the eyes of insects are generally sessile, yet to
give them a wider range they are sometimes, but it rarely
occurs, placed, like those of many Crustacea, on a foot-
stalk, but not a moveable one. An instance of this in cer-
tain male Ephevierce has already been mentioned. In the
Hemiptera De Geer has figured two species of bugs
{Cimicidce) that are so circumstanced ' ; as are also all
the known Strepsiptera K., though in these the footstalk
is very short'': but the most remarkable example of co-
lumnar eyes is afforded by that curious Dipterous genus
Diopsis, in which both eyes and antennae stand upon a
pair of branches, vastly longer than the head, which di-
verge at a very obtuse angle from its posterior part ^

In their Jigure eyes vary much. Sometunes they are so
prominent as to be nearly spherical: this is the case with
some aquatic bugs, as Ranatra, Hydrometra, and several
male Ephemera ^. Very often they are hemispherical, as
in the tiger-beetles {Cicindela L.), and the clocks or dors
{Carabus L.); but in a large number of insects they are
flat, and do not rise above the surface of the head.— ^
With regard to their outline, they are often perfectly
round, as in many weevils; ow/, as in various bees;

" De Geer iii. if.xxxiv. /. 17, ] 8, 24. oo.

*• Mo7i. Ap. Angl. i. t. xiv. no. 11./. 1./. Linn. Trans, xi. i.ix.
f. 1 0. d.

" Plate XIII. Fig. 9. Fuessly Archw. t. vi.

^ Schellenberg Cimices t. xiii. ix./. 1. a. De Geer ii. t. xviii.

502 EXTERNAL ANATOMY OF INSECTS.

ovate, as in other bees {Andrena F.); triangular, as in the
water-boatman [Notonecta). They are also often oblong,
and occasionally narrow and linear; as in that singu-
lar beetle Helaus. In many of the Muscidce they form
nearly a semicircle, or rather, perhaps, the quadrant of a
sphere. The eyes of the Capricorn-beetles {Ceramhyx L.)
have a sinus on then- inner side, as it were, taken out of
them; so that they more than half surround the anten-
nae, before which is the longest portion of them. An
approach to this shape is more or less observed in the
darkling-beetles {Tenebrio L.); but in these the sinus is
not so deep. I may under this head observe, that m
those Mantida that represent dry leaves, and some others,
these organs usually terminate in a spme ^

Though not distinguished by the beauty and anima-
tion that give such interest to the eye of vertebrate ani-
mals, and exhibiting no trace of iris or pupil, yet from
the variety of their colours the compound eyes of insects,
though most commonly black or brown, are often very
striking. Look at those of one of the lace-winged flies
that commit such havoc amongst the Aphides^ and it
will dazzle you with the splendour of the purest gold,
sometimes softened with a lovely green. The lenses^ of
those of Xerios blaze like diamonds set in jetS \ou
have often noticed the fiery eyes of many horse-flies
{Tabanusl..) with vivid bands of purple and green
Others are spotted- and Schellenberg has figured one
( Tliereva hemiptera) % that exhibits the figure of a flower

a Stoll Spectres, &c. t ix.f. 14. /. x./. 38, &c.
b Vol. I. p. 261-. ' Linn. Tram. iiAi supr.

d Schellenberg Mouckes, t. xxvii./. 1, 2. c, d.
^»Ux./.3... ^ Ibid.l.W.f.'i.a.

EXTERNAL ANATOMY OF INSECTS. 503

painted iii red on a black ground. These colours and
markings are all most vivid and brilliant in the living
insect, and often impart that fire and animation to the
eyes for which those of the higher animals are remark-
able. Take one of the large dragon-flies that you see
hawking about the hedges in search of prey, examine its
eyes under a lens, and you will be astonished at the bril-
liance and crystallme transparency which its large eyes
exhibit, and by the remarkable vision of larger hexagons
which appear in motion under the cornea, being reflect-
ed by the retina — all which give it the appearance of a
living eye. This moving reflexion of the hexagonal
lenses in living insects was noticed long since in some
bees {Nomada F., Coelioocys Latr.)»

Compound eyes differ greatly in their size. In some
insects, as Atractocerus, the drone-bee, many male Mus-
cidcE, &c., they occupy nearly the whole of the head ;
while in others, as numerous Staphylinida, Locusta
Leach, &c., they are so small as to be scarcely larger
than some simple eyes of spiders: and they exhibit
every intennediate difference of magnitude in different
tribes, genera, and species.

Under this head I must say something of the Canthus
of the eye; by which I mean an elevated process of the
cheek, which in almost all the genera of the LamelHcorn
beetles enters the eye more or less, dividing the upper
portion from the lower. Though usually only a process of
the cheek, yet in the Scarabceidcc the whole of that part
forms the canthus ^ It only enteis the eye in the Ru-
ielidie, Cetonida, &c. ; it extends through half of it in

* Mon. Ap.Angl.h 148.

•> Plate XXVII. Fic 4. h'.

504.' EXTERNAL ANATOMY OF INSECTS.

Copis; it goes beyond the half in Ateiichus; and m Bys-
sonotus MacLeay {Lucanus nehulosus K.) it quite divides
the eye into two % as I before observed. In Lucaniis,
Passalus-Sic. it projects before the eye into an angle; in
Lucanusfemoralis nearly into a spine; but in Lamprima
and (Esalus it does not exist. The part, also, that enters
the eye in the Capricorn-beetles may be regarded as a
kind of canthus, though it is merely a dilatation of the
front.

^. toJwate^— Having given so full an account of
the kinds and structure of the ordinary eyes of insects,
you may perhaps expect that I should now dismiss the
subject: you would, however, have great cause to blame
me, did I not make you acquainted with a kind of auxi-
hary eyes with which a large portion of them are gifted;
I mean those pellucid spots often to be found on the poste-
rior part of the front of these animals, or upon the vertex,
frequently arranged in a triangle. These, Linne, from
his regarding them as a kind of coronet, caUed Stem-
mata. They have been of late denommated Ocelli ; but
as this latter term is also in general use for the eyelets on
the wings of Lejndoptera, I have adhered to that of the
illustrious Swede. Neither he nor Fabricius has ex-
pressed any opinion as to the use of these organs; but
Swammerdam and Reaumur were aware that they were
real eyes. The former foiind that there are nerves that
diverge to them though not easily traced, and that they

a This circumstance proves that Mr. W. S. MacLeay is correct in
considering this as a subgenus j but it militates agamst its bemg

connected with Lamprima.

^ Platk VI. Fig. 4, 10. VII. Fig. 1, 2, 4. XXVI. Fio. 39-4...I.

EXTERNAL ANATOMY OF INSECTS.

505

have a cornea^ and what he takes for the uvea ^ ; and the
latter has supi)osed that the compound eyes and these
sunple ones have, the one the power of magnifying ob-
jects much, and the otlier but little, so that the former
are for surveying those that are distant, and the latter
those that are neai- The same author relates some ex-
periments tliat he tried with tlie common hive bee, by
which he ascertained that the stemmata, as well as the
compound eyes, were organs of vision. He first smeared
the latter over with paint, and the animals, instead of
making for their hive, rose in the air till he lost sight of
them. He next did tlie same with the former^ and placing
the bees whose stemmata he had painted within a few
paces of then- hive, they flew about on all sides among
the neighbouring plants, but never far : he did not ob-
serve that these ever rose in the air like the others
From this experiment it seems as if the compound eyes
were for horizontal sight, and the stemmata for vertical.

The definition of them by Linne and Fabricius as
smooth, shining, elevated or hemispheric puncta, con-
veys a very inadequate idea of them ; for, except in a
very few instances, they are perfectly clear and transpa-
rent, and their appearance is precisely the same as that
of the simple eyes of Arachnida &c., under which head
they might very well have been arranged ; but as the last
are primary eyes, and the stemmata secondary, it seemed
to me best that they should stand by themselves. The
structure of both is probably the same, and their inter-
nal organization tliat of one of the lenses of a compound
eye, and both are set in a socket of the head.

Bibl. Nat. i. 214. lleauni. iv. 245.

' Ibid. V. 287—.

506

EXTERNAL ANATOMY OF INSECTS.

Though a large number of insects have them, they are
by no means universal, since some Orders, as the Stre-
psiptera, Dermaptera, and Aptera, are altogether without
them. The Coleoptera, also, have been supposed to af-
ford no instance of species furnished with them; but in the
last number of Germar and Zincken Sommer's Magasi?i,
it is affirmed that they are discoverable in Gravenhorst's
genus Omalmm, but not in the kindred genera Micro-
peplus and Anthophagus Upon examining the former
genus, I find, that although Omalium planum and affi-
nities, O. striatulum, and some others, appear not to have
them, yet with the aid of a good magnifier they may be
discovered in most species of that genus; as likewise in
Evcesthetus Grav. I find them also very conspicuous in
A. Carahoides and other AnthopJiagi, but some species
appear to want them. In these insects they are two in
number, situated in the vertex a little behmd the eyes but
within them, and either at each end of a transverse fm'row,
or at the posterior termination of two longitudinal ones.
Nor are they found in all the genera of the other Orders.
In the Orthoptera, the Blattida, unless a white smooth
spot on the inner and upper side of the eyes may be re-
garded as representmg them, have them not; but in all
the other genera of that Order they are to be found
In the Hemiptera all the Cicadiadce are gifted Avith them ;
as are likewise Tetyra, Pentatoma, with many other Ci-

» Magas. der Entomolog. iv. 410.

b Latreille speaks of Phasma as having no stemmata; but it should
seem that he examined only the apterous ones, all the winged indi-
viduals, at least so far as I have examined them, having three very
visible ones. It may, I think, be laid down as a rule, that the larvs
and pupae of Orthoptcra have not these organs. Probably their use
is principally in flying?

EXTERNAL ANATOMY OF INSECTS. SO?

7nicida;, and the ReduviadcB very remarkably ; but many
otliers in both sections of this order, as Thrips, Coccus,
AphiSi Capsus, Miris, Naucoris, Nepa, and Notonecta, &c.
are deprived of them Of the Neuroptera the Libellu-
lina add stemmata to their large eyes, in the anterior
angle of which they are stationed^; but many other ge-
nera of that Order are without them ; as Mi/rmeleo7i, As-
calaphus, Hemerobius, &c. The Trichoptera and Lepi-
doptera universally have them ; though in the latter,
except in Castnia and the Sphingidce, they are not ea-
sily seen. In the Hymenoptera they are usually very
conspicuous, but in JLarra and Lyrops, two genera of this
order, the posterior pair are scarcely discernible ; and in
the neuter ants they are quite obsolete. In the Diptera,
though many genera are furnished with them, yet many
also want them ; amongst the rest Latreille's TipularicB,
and all the horse-flies {Tabanus L..). The Pupipara
{Htppobosca L.) usually have none; but in Ornithomyia
avicularia, one of that tribe, though extremely minute
they are visible, arranged in a triangle, in the polished
space of their vertex.

As to the Number of the stemmata, three appears to
be most universal. Reaumur mentions an instance in
which he counted four in a fly with two threads at its
tail ; but great doubt rests upon this statement Some
Orthopterous genera, as Gryllotalpa, and many Hemi-

* Flata pkaltBnoides F. and afBnities have no stemmata, while
Flata reticulata and affinities have them : a proof that these tribes
ai-e distinct genera.

Plate VI. Fig. 10. i.

" Reaum. iv. 243. He refers for this insect to plate xiv. without
adding any number for the figure ; but no such is in that plate.

508 EXTERNAL ANATOiVIY OF INSECTS.

pterous, as Tetyra, Pentatoma, Bedwoius^ Cercopis,
Fulgora^, &c., have no more than iwo.- and in Larra
and its affinities, as just observed, the posterior ones are
obsolete, so as to leave only one discernible.

Where there are three of these organs, they axe usu-
ally arranged in an obverse triangle in the space behind-
the antennae, at a greater or less distance from them.
In those male flies (Muscidce) whose eyes are confluent,
the stemmata are in a little area behind their conflux ;
but, as before observed, in the drone-bee and the Lihel-
lulina they are before it. This triangle is in some cases
nearly equilateral, as in Perla related to the may-flies,
and many Hymenoptera; in others it is acutangular, as
vaLocusta &c., in which the stemma forming the vertex
of the triangle is before the antenna : in others, agam,
it is obtusangular, as you will see in Pepsis and vari-
ous Hymenoptera. In the humble-bees {Bombus), a line
drawn through them would form a slight curve. Their
situation also varies. In insects that have only two,
they are sometimes placed a little behijid the eyes, or m
the back part of the space between them : this is die case
with most of the bugs (Cme^ L.) that have them.—
They are often distant, as in Tetyra ¥., Edessa F.; and
sometimes approximated, as m Beduvius F.^ In many
of theHomopterous Hemiptera, as Cercopis, Ledra, &c.
they are planted in the ^i^-i^^r part of the heads but in
lassus their situation is on the under part; and in a North
American subgenus, as yet without a name, they are ex-

" Plate XXVI. Fig. 40. i.

1. Cercopis, Ibid. Fig. 42 j and Fulgora, Fig. 41. i.

Plate VI. Fig. 4. i. . , •

0 Plate XXVI. Fig. 40. i. ' Ibul. Fig. 42. i

EXTERNAL ANATOMY OF INSECTS. 509

actly hetvoeen tlie two, being placed in the frontal angle.
In Fulgora their station is between the eyes and antennae*.
They are most commonly sessile, and as it were set in
the head; but in some, as Fulgora cmidelaria, they stand
on a footstalk. The stemmata are set in the side of a
frontal tubercle in that four-winged fly of threatening
aspect, Corydalis, which in its perfect state has mandi-
bles, but longer and more tremendous, like those that
distinguish the lar-va only of the kindred genus Hemero-
bius These organs differ little in shape, being usually
perfectly round and somewhat co7ivex but occasionally
they vary in this respect. In Fulgora serrata they are
oblong, with a longitudinal depression ; in F. Diadema
they are also umbilicated, but the umbilicus is circular;
in Cor-ydalis they are oval; in other insects they are
ovate; in some semicircular, and in a few triangtdar.
They vary nmch in size: in some of these animals being
so minute as to be scarcely visible, while in others, as
Corydalis, Doiylus, Vespa pallida F., Reduvius, Sec",
they are as large as some compound eyes. They differ
also in colour, though often black : in Fulgora laternaria
they are of a beautiful t/^Z^w,. in F. candelaria they are
'mhite; in many Hymenoptera they are crystalline, in
others red : the fierce look of Eeduvius personatus is ren-
dered more hateful by its stemmata having a pale iris
round a dark pupil =.

Let us here stop and adore the goodness of a benefi-
cent Creator, who, though he has deprived these litde
beings of the moveable eyes with which he has gifted the

Plate XXVI. Fig. 41. i.
^ De Geer iii. t. xxvii./. 1. Reaum. iii. t. xxxii./ 3, .Q.
'■■ Plate XXVI. Fig. 40. i.

510 EXTERNAL ANATOMY OF INSECTS.

higher animals, has made it up to them by the variety
and complex structure of their organs of vision, where
TOe have only two points of sight, giving them more than
as many myriads.

5. Antenna.—^ni of all the organs of insects, none
appear to be of more importance to them than their An-
tenncB, and none certainly are more wonderful and more
various in their structure, and probably uses. Upon
this last particular I shall enlarge hereafter. Their
structure, as far as it differs in the sexes, I fuUy dis-
cussed in a former letter ^ and the most remarkable
kinds of them will be included in a set of definitions
which I shall draw up for you before our correspondence
on this part of my subject closes: I shall therefore now
confine myselfto the followingparticulars— namely, their

numher, insertion, substance, situation, proportion, general
form and structure, clothing, expansion, motions, and sta-
tion of repose.

As to their Number, in the majority of crustaceous ani-
mals the antennae amount to four, but no insect has more
than two. A genus recently established [Otiocerus Kir-
byb) seems to afford an exception to this rule, since the
species composing it at first sight appear to have fo7ir,
and in some instances even six antennae ; but as only two
of them terminate in a bristle, the other, though pro-
ceeding from the same bed of membrane, may perhaps
be regarded as merely appendages. Germar, who has de-
scribed a species of this genus under the name of Co-
lax Wintheri, considers these appendages as analogous

« See above, p. 31 8- "
•^^ Mag. der Eiitoviolog. iv. 5.

EXTERNAL ANATOMY OF INSECTS.

511

to palpi : but as they do not proceed from the oral or-
gans, but from the bed of the antennce at the base of the
nose % they ought certainly to be regarded rather as ac-
cessories to the latter, than as representing the former.
In the Aptem order the mites {Acacus L.) appear to be
without these organs. In the pupiparous tribe Hippo-
bosca they seem about to disappear; and in the Arach-
nida &c., as has been more than once observed the
mandibulcE have been thought to represent, not indeed
the antenna of insects, but the inner pair of those of the
Crustacea.

In considering the insei-tion of antennae, by which I
mean their articulation with the head, we must advert
first to the orifice {Twulus) that receives them This
is a perforation of the crust of the head; commonly,
though not mvariably, circular : in Coleopterous insects
often with concave lubricous sides, forming an acetabu-
lum, with processes usual in ginglymous articulations,
larger than the bulb or root of the antennse; and which is
commonly covered, except the central space occupied by
the bulb, with a tense membrane. Though not in gene-
ral remarkable, in some cases it merits attention. In the
genus Bhipicera Latr., the elegant antennae of whose
males I have described in a former letter \ particularly
the Brazilian species, it is a long process on each side of
the nose, and might be mistaken for the first joint: in
another Coleopterous genus, Prioce7-a it has some-
what of the shape of a trumpet : in Cupes a tubercle rises

^ Palpi quatuor, sub^quales, cyXmMd, ad bami cli/pei. Germ.

See above, p. 18, &c. c p^^^^E VI. Fig. 1, 4. i'.

See above, p. 321. Limi. Trans, xii. t. xxi. f. 3.
' Ibid./. 7.

512 EXTERNAL ANATOMY OF INSECTS.

just above the base of the antenna : a circular process
forms the torulus in Fnlgora and others. It is also often
placed in a cavity of the front, as in several wild-bees,
Melitta K., and in Locusta Leach on the sides of an ele-
vation of that part \ In a large majority of insects the
hnVo {Bulbus) or ball which is received by the bed, wears
the appearance, especially in the Hymenoptera, of a di-
stinct joint; but if you carefully examine it, you will
clearly see that it is merely the base of the scape swelled
out into a spherical or other kindred form"; and often
marked, as in the Cicindelida, with impressed points :
as it is the piece by ^^hicll the antenna moves in its soc-
ket, this form of a rotida was doubdess given for its more
ready motion in all directions. This stmcture is prmci-
pally conspicuous in the Coleoptera and Hymenoptera
Orders • in the others the base is not so distuiguished
from the rest of the scape. If you carefully extract the
antennae of a beetle, say a Copris ov Lamia, and examine
ks base or bottom, you will find that it is open for
the transmission of muscles and nerves; that m its up-
per margin it has a deep notch or sinus, on each side ot
which is a smaller notch ; and that all round the margm,
which is very lubricous, a membranous ligament is at-
tached, by which it was affixed in the torulus. Its arti-
culation, therefore, seems of a mixed kind, hke that ot
most other organs and parts of insects, partaking ot the
ligamentous, ginglymous, and ball and socket. In the

a Plate VI. Fig. 4. c. i' . ,
b Plate XII. Fig. 9. 1". This circumstance was very recentl>
discove:ed^ which willaccountforthisplateno^
in this respect, the bulb being represented as a distinct joint
Fig. 6, 10,20. ^

EXTERNAL ANATOMY OF INSECTS. 513

OrtJiopterOy Hemiptera, &c. the articulation seems more
purely ligamentous.

With regai-d to their substance— these, organs are re-
gulated, in some degree, by the nature of the integu-
ment of the animal of which they are appendages; in the
softer insects being of a softer substance than they are in
hard ones. The vertex of the joints, where they receive
the succeeding one, appears in many cases to be softer
tlian the rest of it, and especially towards the apex, often
papillose. The antennae are generally opaque; but in
Nebria camplanata, a beetle common on the sea-coast in
Wales and Lincolnshire, they are semitransparent.

The situation of antennjE must next be considered.
In this respect it seems necessary that they should be
so situated as to be under the direction of the eyes : for
if you examine ten thousand insects (except, as was be-
fore observed % where there are four eyes), you will not
find one in which these organs are situated either above
or immediately behind them; their station being always
either somewhere in the space between the eyes or that
below them. In Ptinus F. they are placed near the
vertex; but in Gibbium, which is so nearly related to
that destructive genus they are beneath them. In
many Melitta K. they are in the middle of the space
between the eyes; and in many other Hymenoptera and
Coleoptera {Staphylinm &c.), in the anterior part of it.
In many LameUicorn genera, as Melolontha, Cetonia,
Lucanus, &c. they may be regarded as planted in the
lower surface of the cheek before the eyes; but in Cb-
pris &c., in which they are inserted further under the

» See above, p. 498. «. Voi,. I. p. 231, 238.

VOL. III. 2 L

514- EXTERNAL ANATOMY OF INSECTS.

shield of the head, they are properly in the prone surface
of i\xe front. In the Capricorn-beetles {Cerambyx L.) and
Cnodalon F. they may be termed ino^^Zar, or placed in
a sinus of the eye ; in the former tribe in its interior, and
in the latter its anterior side. In the Rhynchophorous or
rostrum-bearing beetles [Curculio L.) they vary in their
situation. Thus \n Macrocephalus Oliv. they are inserted
at its apex ; in Anthrihus in its middle, and in Calandra
lit its base \ In the water-scorpions {Nepa, Belostomu,
&c.)they may be called extraocular, being placed under
the' head in its prone part, outside the eyesK In Nir-
mus Fringilla^, a kind of bird-louse, they appear to be
oral being situated, according to De Geer, under the
head near the mouth, at a great distance from the

^^In 'then- proportions, both as to length and thickness,
antenna vary extremely. Thus sometimes they are very
short-much shorter than the head; as in the aquatic
beetles Gt/rinus, Parnus, and the water-scorpion; and
some land-beetles, as Anthrenus, &c. At other times they
far exceed the length of the insect: the males of many
Capricorn-beetles are so distinguished. In that of Lamm
cedMis they are more than^r times as long as the
body; and every intermediate length between these two
may be found amongst them. They vary also greatly m
thichiess : in Paussus, whose antennae emit light m the
night ^ and Cerapterus, they are nearly as thick,-at
least their knob, which forms the chief part of them,-as

« Oliv. Ins. no. SO. Macrocephalus t.lf.l-U AnthrMsf.h^\^^ ,
and no. 83. Curculiot.W. Calandra f. 16.

<- Schellenberg Cirnicw t. xiv./. \.l>. , y , tt n API
c De Geer vii. Liv.f.7-aa. ' ^ o^.. .i- -

EXTERNAL ANATOMY OF INSECTS. 51.5

the body of the, insect while in Mantis, Acrida K. and
PsocHS, they are as slender as a hair. The antennce in
many of the P? 'loni, especially in P. imbricornis, are thick
from base to tip ; while in other Capricorn-beetles they
are quite the reverse.

It will not be necessary to enlarge here upon the ge-
neralyo?TO of these organs : I shall therefore only notice

the two principal divisions of them in this respect.

Antennae, regard being had to one of their uses, may be
divided into two sections, distinguished by forms ex-
tremely different : those, namely, that are employed by
insects as iactors to explore their way, and those that
cannot be so employed. The great majority are of the
former kind ; but those that may be denominated setige-
rous, — as the antennas of the Libellulina, Ephemerina, of
the Homopterous Hemiptera, and of many Diptera, the
last joint of which terminates in a bristle, or is furnished
with a lateral one, and of some gnats that have short
feathered antennae,— appear not fitted to be used as tac-
tors to explore by touch, and form the latter description.
This difference in tliese organs, as I shall have occasion
to prove more at large hereafter, furnishes a strong pre-
sumption that their primary function is not touch. Were
this the case, it would be common to them all.

As to their structure, antennae consist in general of a
number of tubular joints ; each of which having separate
motion, the animal is thereby enabled to give them every
flexure necessary for its purposes. The scape, or first
joint, by means of the bulb inosculates in the tai ulus, or
is suspended to it; and the others, sometimes by a simi-

» Plates XII. Fig. 28; and XXV, Fig. 0, 24.

2 L 2

516 EXTERNAL ANATOMY OF INSECTS.

lar, though less pronounced knob at their base, inoscu-
late in the preceding one; but in some cases the inoscu-
lation seems not so perfect, the joints being simply sus-
pended by ligament. In pectinated or lamellated an-
tennae, the branch is usually a lateral process of thejomt
from which it issues ; but in Phengodes {Lampyris plu-
viosa L.) its involute plumose branches appear to articu-
late with the apex of each joints I have a specimen
of one of the Cleridce, of a genus undescribed, in which
each branch is forked. In some tribes of the Capricorn-
beetles {Stenocorus, &c.) the antennae are often armed at
their apex with spines, sometimes on the upper side and
sometimes below. In some aquatic beetles {Gtjrinus,
Parnus) they are furnished with an auricle at their base,
which, like the lid of a box, shuts them in when unem-
ployed, and protects them from the water ^

The portions into which antennae may in general be
considered as divided, have been sufficiently explained
to you above ; but it may not be amiss to add here a few
words on the principal variations in their structure that
I have had an opportunity of observing. The scapus '^
or first joint, which includes the bulbus, is usually the
most conspicuous joint in the antenna (exclusive, I mean,
of the capitulum, in those in which tliat organ terminates
in a knob), it being thicker and often longer than the suc-
ceeding ones. In the Capricorn and Darkling beetles,
indeed {Cerambyx and Te7iebrw L.), the third joint is the
longest, but the scape is still the thickest; and in the
stag-beetles {Lncanus L.), many of the weevil tribes

a Plate XXV. Fig. 4.

" Plates XII. Fig. 29 ; and XXV. Fig. 28. a.
' Plates XI. XII. XXV. k' .

EXTERNAL ANATOMY OF INSECTS.

517

{Curcidio L.), and those of the bees {Apis L.), except in
the males, it is as long nearly as the remainder of the
antennae, which forms an angle with it. In shape it is
generally somewhat curved and subclavate, or increasing
in size from the base to the summit; but it is sometimes
straight and filiform, at others oblong or square, at
others again triangular, in several instances three-sided :
in one {Cetonia cruenta F. Gemichus K.) it is, as it were,
broken, the upper part forming nearly a right angle with '
the lower; in Cerocoma Schcefferi it is foliaceous; and it
is occasionally suborbicular : and probably many other
forms might be enumerated.

The Pedicellus^ is the second, and may be deemed the
least conspicuous joint of the antennae. Though more
slender than the scape, it is generally thicker than that
which immediately follows it. In broken antennae it is
die hinge or pivot on which the clavola or upper mem-
ber turns : it is usually very short, campanulate or bell-
shaped, or obconical ; but in a species of bug ( Tetyra,
from New Holland— T. pedicellata Kirb. MS.) it is
nearly as long as all the rest of the joints taken together.
In those species of Lycus, a genus of beetles related to
the glow-worm, that have flattened antennae (as L. reti-
culatus,fasciatus, &c.), this joint is almost received into
tlie socket of the scape, so that their antenna? appear at
first to have only ten joints, but in those which have
those organs filiform (as L. minutus, Aurora, &c.) it is
more conspicuous.

The Clavola^, or remaining joints of the antennjE
taken together, constitutes the principal part of the or-
gan, which, especially at its extremity, exercises its func-

» Plates XI. XII. XXV. 1'. * Ibid, m' .

518 EXTERNAL ANATOMY OF INSECTS.

tions of touch, or any other sense. The principal varia-
tions, as to form and structure, that occur in this part
will be mentioned in another place, I shall only here
observe, that in many instances the first joint of this part
is longer than the rest ; but in Tetyra pedicellata just
mentioned, it is by far the shortest, and shaped like the
pedicel of mo-t insects. In the Libellulina, the Homo-
pterous Hemiptera, and those flies whose antennae ter-
minate in a bristle, the clavolet is represented by the
bristle. But in the flies which have a lateral bristle, on
the last joint, and those with triarticulate antennas that
have no bristle, the terminal joint represents it. The
clavolet often terminates in a knob, or in several joints
thicker than that which precedes them. This varies
greatly, not only in its form, but also in the number of
joints of which it is composed. Thus in Paussus, Platy-
pus, and many Calandrcc, it consists of only a single
joint in Anthremis, Ditoma, &c. of too,- in Nitidula,
Geoimpes, cScc. oUhree^; in Teiratoma, the Silphidce, of
four''; of Jive in Scaphidium^ ; of six m one species of
Languria ; of seve7i in the common cockchafer {Melo-
lontJia vulgaris^); of eight in Diaperis Boleti, in which
the whole clavolet forms the club^; of nine in Oenas; and
ten in Cerapterus s. All the above, you will observe, are
beetles. In the other orders there are eleven joints in the
knob of some butterflies ; twelve in that of Ascalaphis ^
and Myrmeleon; and lastly, fourteen in Tracheitis K

•■• Plates XII. Fic. 38; and XXV. Fig. 13. m".

Plate XXV. Fig. 3, 5,21. m".
< Plate XII. Fig. 10. m". " Ibid. Fic. 4. in".

Plate XXV. Fio. 1. m". < Plate XI. Fig.

« Plate XXV. Fig. 24. " IH^L Fjg. :30.

' Jurinc JQ/mcnvpl. I- vii /. H.

EXl'EUNAL ANATOMY OF INSECTS.

Under structure also, the number of joints of which
antenna? in general consist, should be considered. If
you examine the insects belonging to the different or-
ders, yon will find remarkable variations in this respect.-
Let us run through them :— In the Coleoptera the na-
tm-al number of joints is eleven ; but this rule is not
without many exceptions. Thus, many have fexver than
the prescribed number : Paussus has only two % Clavi-
ger and Platypus five, Dorcatoma and Calandra eight'',
Geniates K. and Phancmcs MacLeay nine and lastly
Melolontha ten ^. Others, again, have more than eleven
joints : Cchrio Gigas, Chrysaviela stolida, some Sapei-dcCy
imd several others, have twelve. In Prionus imbricornis
the female has nineteen, and the male twentij ^ iniipi-
cera marginata has thirty-two ; and in a New Holland
species of this genus I counted thirty-eight. In the Or-
thoptera I can trace no general law in this respect. In
Locusta Leach in some species you may count fauHeen
joints, in others sixteen, and in others twenty-Jive. In
one, which appears to be a pupa, I found only thirteen.
In Mantis they Gxceedthirty ; but mBlatta, from between
thirty m\<\ forty, they reach nearly 07ie hundred andjifty;
often varying in number in different individuals of the
same species. The order Hemiptera exhibits two pecu-
liar types of antennae, which, with some exceptions, di-
stinguish the two natural sections into which M. Latreille
has judiciously divided it. In the Heteropterous section
they are without a brisde at their end ; and in tlie Hovw-
pterous one, with the exception of Aphis, Thrips, &c.

Plate XXV. Fig. 28. <• ll,id. Fig. 13.

• Ibid. Fig. ,1 .i n.-^i. ].

" f'' -^'^ ^- 1''^;. 13. ' Linn. Trans, xii. i. xxi f. 3.

520 EXTERNAL ANATOMY OF INSECTS.

they have one. In the genera of both these tribes, the
number of joints varies in these organs. Thus, exclu-
sive of the seta, in Flata and Cixius there are only tm
joints; m Galgulus, Fulgora, and Cercopis, there are
three; in Lygasus, Coreus, &c. there are four; in Teti/ra,
Pentatoma, Tettig07iia,ihex&axeJive^\ mAleyrodes there
are six; in Aphis seve?i; in Thrips eight; in Psylla ten,
the last of which is terminated by two bristles''; and in
Coccus eleven. The Neuroptera order, as it stands at
present, is regulated by no general rule with regard to
the number of joints in the antennas of the insects that
compose it. Several types of form in these organs distin-
guish its discordant tribes. The Jrst is that of the Ephe-
merce, in which the antennas consist of two short joints,
crowned by a short, tapering, unjointed bristle. The second
is that of the Libellulina, similar to the above, but with a
jointed bristle. The third is that of Psocus, in which the
antenna has two short thick joints at the base, terminated
by a long filiform bristle, consisting of seven or eight
joints, and finer than a hair. Perhaps these three may
be regarded as belonging to a common type. The fourth
type is presented by the short filiform antenna of 7>r-
mes; the ffth by the setaceous ones of Cojydalis, Heme-
rohlus, &c.; and the sixth and last by the clavate and
capitate ones of Myrmeleon and Ascalaphus. In the
Lepidoptera and 2'richoptera orders the antennas, though
varying in their general form in the three tribes of which
Linne formed his genera Papilio, Sphinx, andPhalcen^,
with the exception of Hepialus, in which the jpints axe.

» LatreiUe says *Lr, but only /I'e are discernible; the three last
form a kind of bristle,
^ Latr. Foumis, 323.

EXTERNAL ANATOMY OF INSECTS. 521

few, are always multiarticulate : — we will therefore, with-
out further delay, proceed to the Hymenoptera. In La-
treille's tribe Aculeata the general rule is, that the fe-
males shall have twelve joints and the males thirteen.
In his Ichneumonides the law seems to be, that the an-
tennae shall be multiarticulate and setaceous; but in most
of the other tribes of the order, even those that in other
respects are most nearly related,— as in his Tenthredine-
tcE, — theniunber of joints of these organs varies without
end. Thus in Hylotona there are only three joints
in Cimbex Iceta^Jlve; in C. axillaris and Perga Leach %
six : and so on to twenty-five or more The same fluc-
tuation in this respect runs throughout the rest of the
order. In the Diptera there are two general types of
antennae:— those of the Tipular ia Latr., consisting usu-
aUy of from fourteen to sixteen jomts, in the males often
resembling beautiful plumes ; and those of the remainder
of the order, in which they do not exceed three joints «=:
though the last, or patella, is often further divided into
obsolete or indistinct ones These antennae may be
further subdivided into Jilatce and aristatce, or those
without and those with a bristle, either lateral or ter-
minal.

The clothing of antennae also merits attention, since it
is often not a little remarkable. By clothing I under-
stand the down or hairs of every kind with which they
are either generally or partially covered. A great number
of filiform aud setaceous antenna of Predaceous beetles
{Cicindela L., Carabus L.) have the first two, three, or

Jurine Hi/mcnopt. L vi./, 3. " Ibid./. 2.

- Ibid./. J . Plate XXV. Fig. 7. Plate XXV. Fig. 25, 26
« Plate XII. Fig. 16-22. f Ibid. Fig. 19. a.

522

EXTERNAL ANATOMY OF INSECTS.

four joints naked, and the rest covered witli a fine down.
In insects that have a knob at the end of these organs,
whether lamellated or perfohate, this down is often con-
fined to it, or to its intermediate joints, and seems inter-
mixed with nervous papillae. These are particularly vi-
sible in the flabellate antennoe of liltipicera^ Lamjjyris
Latreillii S Elater f ahellicornis &c. covering both sur-
faces of the processes of the joints. In some male bees
these papilke are inclosed in hexagonal spaces into which
the antennae are marked ouf^. It is to be observed,
that in many antenna? the joints of the clavolet have one
or two bristles or more at their apex, one above per-
haps, and one below ; the lower angle in those of the
serrated antennae of Elater is usually so furnished, and
sometimes the upper. In many Capricorn-beetles and
various insects the antennae are clothed, instead of down,
with stiffish hairs or short bristles. Other insects have
these organs, at least the clavolet, beset with longer haire
standing out from them on all sides: of this kind are
those of a singular beetle {Sarrotrium muticum) some-
times found in this country''. Again, there are some
that have only their underside bearded with longer haii-s;
as Lamia curadio?ioides, spcculifera K., and other Ca-
pricorns «=. In another of this tribe, Saperda hirsutkor-
7iis, the three intermediate joints are ornamented with
branches of long black hairs, which give them an elegant
and feathery appearance In Callichroma alpina the

=- Linn. Tram. xii. t. xxi./. 3, 4. PtAxr XXV. Fig. 11.

Plate XI. Fig. 17-
. JXirby Man. Ap. AngL i. 184. x. cl. 1. f. 8.
" rr,ATr, XXV. F.G. 27- ' ^^^^'^^

Plaxk XXy. Fi&. 32.

EXTERNAL ANATOMV OF INSECTS. 523

apex of ihe slate-coloured joints of its antennae is bearded
with ijlack hairs. In Lamia retiadata^ and Saperda
fa&cicidata and plumigera, all also Capricorns, a single
bunch of hairs, resembling the brush of a bottle-cleaner,
signalizes the middle of the antenna * : in Saperda sco-
pulicornis K. this is star-shaped Sometimes the scaj)e
is externally bearded, as in Trox^ a beetle found in horns
and bones ; and in many other Lamellicorns In this
last tribe the two exterior leaves of the knob of the an-
tennae are often set with short bristles and in a minute
beetle called by De Geer Dermestes atomarius^ the hairs
of this part are said to form a brush ^

When insects, I mean more particularly Coleoptera,
are about to move from any station Avliere they have
been at rest, the first thing they usually do, before they
set a step, is to bring forward and expand their antenna),
which have either been carefully laid up in a cavity fitted
to receive them, or back upon the body : if they termi-
nate in a lamellated knob, they separate the lamellce as
far as possible from each other; or if it is perfoliate, the
joints of it mutually recede. The object of this is evi-
dently to collect notices from the atmosphere, shice the
papillose part of these joints cannot be applied to sur-
llices. When the animal begins to move, in many cases
the antennae do the same, and continue their motion till
it stops and returns to a state of repose. In the parasitic
tribes of the Hymenoptera {Ichneumon L.) they are kept
in an almost constant vibration. Many other insects
move them ui all directions without any order or regu-

" Platk XII. Fig, 25. '< Platj; XXV. Frc. 17.

Linn. Trans, xii. f. xxiii./. .")./. ' Ibid. i. xxi.y. 8 g. {), 10. c.
* Dc Gccr iv. 1. viii./, 20.

524- EXTERN.VL ANATOMY OF INSECTS.

larity ; and othersj when they elevate one depress the
other, and so proceed as if balancing themselves by
means of these organs like a rope-dancer. I have before
stated to you how by motions of their antenna, ants and
bees communicate their wants or discoveries to each
other, or make inquiry concerning any thing they Avish
to know ^. But as I shall have occasion to make some
further remarks upon this subject, when the senses of
insects are under discussion, I shall for the present take

my leave of it.

I shall conclude what I have to communicate to you
relative to the organs of which we are treating, with a
few observations with respect to their station when the
insect reposes. In the Capricorn-beetles, Eticera and
other insects with long antennas, they are merely turned
back or on one side with no particular cavity for their re-
ception when unemployed, but probably the apex passes
under the body. In the Predaceous and DarkHng bee-
tles {Carahusl.. Tenehrio L.) their station is usually un-
der the sides of the prothorax, and in the Tortoise bee-
tles {Cassida), under its anterior margin. In the Elastic
beetles {Elater) they are received into a groove between
the under margin of that part and the fore-breast {ante-
pectus). In Anthrenus, when the animal reposes or
counterfeits death, the antennae are concealed in a ca-
vity of the underside of the protliorax, at right angles
with the throat". In the kindred genus Byrrlms, another
simulator of death, a large cavity is excavated under the
same part, to receive both the forelegs and antenna, a
narrow space being left between the angle of thepo-

^ - Sec Vol. II. p. Go, 201-. " De Geer iv. ^vii-/- 33.

EXTERNAL ANATOHIY OF INSECTS.

525

thorax nnd fore-breast exactly julmitting the base of the
latter, which are quite concealed under the former. In
Cjyptocephalus and ChlamySy kindred beetles, when at
rest they are withdrawn, except their scape and pedicel,
with the head within the cavity of the pj-otJiorax. Jn
others they are turned under the head, without any par-
ticular cavity for their reception; as in many moths,
Apion, &c. In most of the Lamellicorn beetles their sta-
tion is in the cavity formed by the eye and the throat,
the knob forming an angle with the rest of the antenna.
In Heterocerus they follow the contour of the eye ^. In
Brentus, a genus of weevils remarkably long and slen-
der, they are turned back and received by a slight lono-i-

T • 1 'Oft

tudinal cavity of the rostrum ; but in those of this tribe
{Curculio L.) in which the clavolet forms an angle with
the long scape, this latter part, bending back, is laid up
in an oblique channel of that part; and the former,
pointing in the contrary direction, is folded upon it. In
many flies {Muscidce) a vertical frontal cavity receives
the antennae, which point downwards during repose ^
Crxjptocenis, a very remarkable ant, lias on its head a
singular square plate, the sides of which form a deep
longitudinal cavity: in this cavity the antennse, quite
concealed, repose in safety. A cavity equally remark-
able is exhibited by the water-scorpions, particularly
Belostomuy in which is a verij deep kidney-shaped box,
between the eye and throat, to receive and defend its
singular antennae <=; which, when they are reposing, is
closed by the exterior harder joints, and from which it
seems as if they turned out, like a sentinel out of his box.

» Pr.ATE XXV. Fic. 35. ^ De Geer vi. /. i. r 5

<= Pr.ATF. XI. Via. 21.

52G EXTERNAL ANATOMY OF INSJ-ICTS.

In some aquatic genera of beetles, as Gyrinm, Parmis,
&c. they are withdrawn within a lateral cavity of the
same part, and are defended from the water externally
by the auricle at their base ^ The flabellated and la-
raellated antennte, previous to their being folded for4:e-
pose, close all their plates; which in action are as widely
expanded as possible, so as to form a knob; and in some
the middle piece is entirely concealed, as if in a box.
In broken antennse, or those in which the clavolet forms
an angle with the scape, the former is folded upon the
latter, with its point downwards.

II. Suhfacies.—hU\\rig dispatched the Fades, or up-
per side of the head, I am next to consider the Suh-
fades, or under side: but as the principal parts that oc-
cupy this side have been already considered, I shall have
no occasion to detain you long.

i. JM^Mte^— This part, which may be regarded as
analogous to the throat in vertebrate animals, lies between
the cheeks; from which it may usually be distinguished
by being more lubricous and tumid, and often separated
by an impressed line. It is particularly conspicuous and
elevated in the Lamellicorn beetles, and calculated by its
lubricity for easy motion in the lower side of the cavity
of the chest. Its apex is the base in which the mentnm
sits. It is not necessary to enlarge further upon it, as it
seldom exhibits striking characters.

III. Collum^.—ln a large proportion of insects the
head inosculates in the trunk without the intervention

" Pf.ATE XIT. Fir,. (t.

^ Plate VI. m.

- Ibid.

EXTERNAL ANATOMY OF INSECTS.

527

of a neck, or a constriction of the head behind. In the
Orders Orthoptera^ Trichoptera, Lepidoptera, Hymeno^
-ptera, and Diptera^ no instance of it that I recollect oc-
curs : in the Coleoptera there are many. In tlie Preda-
ceous beetles, though several have no distinct neck, yet
others, as Anlhia^ &c. hiive a short and thick one ; and
some few, as Colliuris, Agra, &c. one more pronounced,
Latreille has named a tribe in this Order Trac?ielidcsy
from the circumstance of their having a neck: in this
tribe you will find the blister-beedes {Cantharis and My-
lahris) both of the moderns and the ancients. In die
Hemiptera order the water-scorpions Nepa, &c, have a
tliick short neck: and Zelus, (a kind of bug,) one longer
and more slender ; and, like Raphidia, the snake's-head
fly, which is similarly circumstanced, has the air of a
serpent. Other Neuroptera, likewise, have a neck; as
Ht-merohius, Corydalis, &c. This part presents no other
features that merit nodce.

IV. Myoglyphides ^— The Myoglypkides, or muscle-
notches, are sinuses, some shallow and some deeper, in
the posterior margm of the upper side of the head, to
which the levator muscles are affixed. They seem prin-
cipally confined to the Coleoptera; though, in some
cases at least, they may be traced in the Heteropterous
Hemiptera. These notches vary in number and depth
in different insects. Thus in Buprestis there is only one
deep one'': in Copris there are tiw shallow ones, in a
deep sinus separated by a small prominence <= : in Elater
and Lamia there are also two not in a sinus ; and in Ca-

Plate XXVIf. F,g. 1, ?,-5. n'. Ibid. Fig. S

'■ Ibid. Fig. 4.

528 EXTERNAL ANATOMY OF INSECTS.

landra Palmarum there are four, two on each side, with
a prominent lobe between them To each of these
notches, at its under margin, below the ligament that
unites the occiput to the trunk, a muscle to raise the
head is usually attached.

» Plate XXVII. Fig. 1.

LETTER XXXV.

EXTERNAL ANATOMY OF INSECTS,

CONTINUED.
THE TRUNK, AND ITS PARTS AND ORGANS.

As the head of insects is the principal seat of the organs
of se?isatwn, so is the t7^nk of those of motion; and in it
are contained the muscles by which they are moved: it
may therefore be regarded as the great centre of motion,
and as the main support and prop of the two other pri-
mary sections of the body-the head and abdomen, be-
tween which it is situated-it may be deemed the most
important part of the insect, the key-stone of the whole
structure. In treatmg upon it, for the greater clearness,
I shall consider its substance, genei-al form, proportions,
^ompositio?i, i7iternal processes, a.nd members. It will first,
however, be necessary to assign my reasons for the no^
menclature of its parts that I have adopted.

Had the entomological world been universally agreed
upon this subject, and there was an established system
of OrismologyS I should have proposed no alteration
without great reluctance, and the fullest conviction of the
absolute necessity of some change; but as the standard

siLiZ ''"'T ^hkh induced the authors to use this word in-
stead of Tenmnologj/, before employed, see Vol. I. Pre/, p. xii-
They are gratified to see that M. LatreUle has adopted this tem
the work quoted on the other side, p. 1 94.
VOL. nr. 2 m

530

EXTERNAL ANATOMY OF INSECTS.

of language in our science is still unsettled, and different
terms are used by different writers, there seems full li-
berty left to me to select those that appear upon the
whole most appropriate ; and where proper and signifi-
cant terms seem wanting, to invent new ones. M. La-
treille, in a late Essay % has proposed many changes of
this kind, and seems to hesitate concerning the adoption
of some of those recently coined in France for the parts
of the trunk''; it may therefore, I think, be permitted
me to labour a little in this hitherto imperfectly cultured
field, and to suggest such improvements as the subject
may seem to require or admit.

Linne called the part we are now considering the
trunk, its upper-side he usually denominated the thorax,
and its under-side the breast : he notices also the saitel-
lum and sternum". As the prothoraa: and scutellum are
the only apparent parts of the back of the trunk in his
first Orders {Coleoptera, Hemiptera L.), the rest being
covered, in noticing these he puts the part for the whole,
calling the prothoraa; the thorax, but which strictly was
not synonymous with what he called by the same name
in the other Orders. Linne's phraseology with regard to
the trunk of insects was adopted by Fabricius and other
Entomologists, till Illiger employed the term thorax to
designate the whole of the trunks calling the upper part
thorax superior and the lower thorax inferior. M. De
Blainville, M. Latreille, and other French writers, im-

■■^ Organisation Exterieure des Insecles, Mem. du Mus. L viii.

^ Ibid. 199-. I liavc never been able to procure M. Audoni's

Memoire on this subject.

Ftmdame7iL Entomolog.'m Amocn. Acad.yn.U^.

J Tcrmimlogie, 1578, &c. He afterwards called the trunk Sfeth-

dimn: Terminohgie der litse/den. Magaz. 180G. 14.

EXTERNAL ANATOMY l)F JNSECTS. 53I

proved upon this, naming the upper part the back {dor-
sum), and the lower the breast (pectus); and dividing the
trunk, or according to them thorax, into three sections,
eacli bearing a pair of legs. But I see no sufficient reason
for this alteration— the terms trunk, thorax, and breast,
m the common acceptation are well understood, and lead
to no confusion or glaring impropriety; I shall therefore
adhere to the old phraseology, especially as French En-
tomologists in popular language still do the same.

As to the division of the trunk into segments by M. La-
treille and others, it has been regarded as consisting of
Mr^^ primary ones, which have been called in the order
of their occurrence, reckoning from the head—pivthorax,
mesothorax, metathorax. The first of these segments,'
however-and the learned Entomologist just named seems
to hmt as much =>— is usually more distinct fi-om the other
two, than they are from each other. If this idea be cor-
rect, the trunk is properly resolvable into primary
segments, the first bearing the arms or fore-legs, and the
other the proper legs and the organs of flight. M. Cha-
brier calls the latter tronc alifere, or wing-trunk ;-a
happy term, wiiich I have adopted and latinized, call-
ing It thealitrunk {alitrunais): the first segment, because
It bears the fore-legs, I have named manitrunk {mani-
truncus). I adopt likewise the terms above mentioned,
prothorax, mesothorax, metatho>'ax, to signify the three
segments into which the thorax of Linne, or the upper
side of the trunk, is resolvable; and those of the breast
1 denoimnate antepectus, medipectus, and postpectus. If
terms be thought necessary to designate the two intire

Orgniihation, ^r. 19t5.
2 M 2

532 EXTERNAL ANATOMY OF INSECTS.

segments into which the alitrunk is resolvable, the first
may be the meditrunk {meditruncus), and the other the
potrunk {potruncus).

I. Substance.-With regard to its substance, the trunk
in general is softer than the head, and harder than the
abdomen, especially as to its upper surface ; but in some
cases, where it is not protected by the elytra, as in the
rove-beetles {Staphylinus L.), the abdomen appears as
hard as the trunk. Though usually not very different
from the elytra in this respect, in Meloe, Lytta, and other
vesicatory beetles, it is of a firmer consistence.

II. Genei-al Form.-ln the Coleoptera Order the only
part of the trunk that is visible on its upper-side is the
Irothorax : the mesothorax, with the exception of the
tellum, and the metathora., being entirely concealed by
it and the elytra; so that, with regard to shape, it may
nearly be considered as merging in the prothorax. Be-
low it is more visible, and may be stated as more or less
quadrangular; in oblong beetles inclining to a parallel-
Lam, Tnd in shorter or hemispherical ones to a square
In the majority it is more convex below than above, except
in the case of the hemispherical or gibbous beetles (C.c-
cinella, Erotylus, &c.), in which the under-side is flat and
the upper-side very convex. In the Drurnal Leprdo-

trunk approaches to a cubical sl^pe, in
Nocturnal it is more spherical A similar ^^^^^^l^^
tains in the Hyuenoptera and Drpte^^a: - *ej-^^^
wasps and flies, the trunk approaching to the figure ot
a sphere; in the ants, Scoli., crane-flies, &c. to that of
a cube. The upper part of it in many Ickneunon.d.,

EXTERNAL ANATOMY OF INSECTS. 533

female ants, &c. is very elevated, forming an arch, and
sloping towards the abdomen. In general it may be ob-
served with respect to the remaining Orders, that the
form of the trunk merges in that of the whole body, the
tendency of which is often to a three-sided figure.

III. Proportions. — The trmik is usually longer and
larger than the head and longer than the abdomen, but
not wider : but there are exceptions to both these rules.
In Colliuns, Maritis, &c., it is more slender; and in Atta
megacephala and some neuter ants, it is shoi'ter than the
head; in Atractocerus, many Staphylinidce^ Phasma^ the
Libellulina^ the Lepidoptera^ and various Hymenoptera,
it is shorter, and in the Mantidcc more slender- than the
abdomen. The greatest disproportion between it and the
last part is exhibited by the genus Evania, parasitic
upon the BlattcB^ in which the abdomen appears merely
as a minute and insignificant appendage of the trunk.
The vertical diameter of this part, almost without ex-
ception, is greater than that of either head or abdomen.
When we consider that it contains the muscles that move
both the organs of flight and the legs, we see clearly the
reason why the Creator gave it greater volume.

IV. Composition. — I lately intimated to you that the
trunk, though resolvable into three segments, in most
cases properly consists of only fwo primary ones. Who-
ever examines the perfect insects of every Order, except
the Aptera S will find this distinction strongly pointed

" In Nirmus Amerk, &c. however, in this Order, the same distinc-
tion is observable.

53'i EXTERNAL ANATOMY OV INSECTS.

out, not only by the different direction of the first pair of
legs from that of the two last, but also in a large pro-
portion by a deep incisure ; and in all it is further mani-
fested by the anterior segment having a motion distinct
from that of the rest of the trunk, and separating readily
from it; and this not only where it is large, as in insects
that have a thoracic shield, but also in those in which
the prothorax is less apparent : whereas the other two
pedigerous segments have little or no distinct motion,
will not readily separate from each other, and in some
cases exhibit no pectoral suture between them. Some-
times, however, these two last segments are more promi-
nently distinguished : in Li/tta, Mi/labris, and other ve-
sicatory beetles, they are separated below by an incisure,
or rather the first or mid-leg segment, is not nearjy so
elevated as that of the hind-legs. In some ants {Atta
Latr.), in the neuters, there is no distinction of segments
in the trunk; but in others {Formica Latr.) it foUows the
general law, and consists of three. In the Arachnida,
with the exception. of GflZeocZ^s, in which the head is di-
stinct, and the three segments of the trunk may be traced,
these parts together form only a single segment In-
duced by these reasons, I consider the trunk as consist-
ing in general of two primary segments, the ma7iitrunk
and alitrunk: the latter resolvable into two seco7idary
ones.

* Manitnmcus\—i:hQ manitrunk, then, is the ante-
rior section of the trunk, which bears the arms and con-
tains the muscles that move them. This part has free
motion, or a motion independent of that of the rest of the

- Plates VIII. & IX. d.

EXTERNAL ANATOMY OF INSECTS.

535

trunk. This indeed seems a necessary result of the di-
rection and uses of the arms. It consists of an upper
and lower part — the prothorax and antepectus.

i. Prothorax ^. — The upper part of the manitrunk in
the Coleoptera, Orthoptera, and Hemiptera, is by far the
most conspicuous part of the trunk, but in the other Or-
ders it is less so. With respect to it, insects may be di-
vided into two classes — those that have and those that
have not a prothorax. In the Coleoptei a Order it is re-
markable both for size and variations in its shape and
sculpture. In the Orthoptera, though less various, it
is almost equally conspicuous, especially in Blatta. In
the Hdmoptermis section of the Hemiptera^ in many ge-
nera it has become extremely short ; while in the Hete-
ropterous section its dimensions are not much reduced.
In the majority of the Neuroptera, likewise, it is compa-
ratively large ; in the Libellulina much shorter, and in
the Trichoptera and Lepidoptera nearly evanescent —
In the Hymenoptera and Diptera, with very tew excep-
tions, the thoracic shield altogether disappears, at least
if I am correct in an idea, which I shall hereafter explain,
that the collar usually regarded as the analogue of the
prothorax, is really a part of the alitrunk. In these last
Orders, though there is no true prothorax^ the mani-
trunk still remains under the form of an antepectus,
bearing the fore-legs, and containing the muscles that
move them. ,

The prothorax of insects may in general be considered

" Plate VIII. «.
If the head of any inilividual of these two Orders be carefully
taken off, it will be found that above there is a very short piece repre-
senting the prulhorax, and quite unlike the collar of Hymenoi^lcra.

.536

EXTERNAL ANATOMY OF INSECTS.

with respect to its parts, margin, appendages, shape,
sculpture, clothing, onA proportions,

1. The prothorax, regarded as a whole, distinct from
the antepectus or fore-breast, consists commonly of fwo
pieces — the shield, or upper part and the ora, or under
part In the shield you are to observe its apex"^, base^,
sides ^, limh^, and dislc^. The apex is the part next the
head; the base that next the abdomen the limb the cir-
cumference, and the dish the central part. In many Or-
thoptera and Heteropterous Hemiptera, the shield ap-
pears further to consist of two pieces, an anterior and
posterior one. The ora is a continuation of the shield
below the lateral margin, turned downwards and in-
wards towards the fore-breast and the legs, but separated
from the former in most cases by a suture, as in Cara-
bus L. ; and in others merely by an impressed line, as in
Blaps F. ; but in Curculio and Cerambyx L., &c. there is
no ora, the shield being without a lateral margin, and
forming one piece with the antepectus. The part we are
now considering varies in different genera. Sometimes
it is very narrow, as in Scarites ; at others very b7-oad, as
in Buprestis, Nepa, &c. In Lampyris, except L. italica,
and affinities, it projects posteriorly into a lobe or tooth,
which forms a right angle with the rest of the ora, and
becomes the lower part of the cavity that receives the
head ; and in Dermestes this part is excavated into an
anterior and posterior one which admits the antennas and
arms when folded for repose.

2. The margin of the prothorax is a ridge, either de-

» Plate VIII. Fig. 1. Ibid. Fig. 2. d.

• Ibid. Fig. 1, 10. a. '' Ibid. b.

« Ibid. c. f Ibid. b. " Ibid. a.

EXTERNAL ANATOMY OF INSECTS.

537

fining its sides or whole cu-cumference. In many cases
this margin is broad and dilated, but in others it is merely
a thread or bead that separates the shield from the cn a.
Though generally terminatmg the upper surface, it some-
times, as in Staphylinus, dips below it. In many insects,
however, as I just observed, the thoracic shield has no
lateral margin whatever.

3. Various and smgular are the appendages with which
the prothorax of numerous insects is furnished. Many of
these are sexual distinctions, and have been before de-
scribed toyou%- but there are others common to both

sexes, the most remarkable of which I shall notice.

Some are distinguished by a long horn which overhangs
the head, as Memhracis cultrata, ensata, &c. in others
it stands upright, as in Centrotus spinosus"; C. Tau-
rus has a pair of thoracic horns hke those of a bull,
only dorsal''; in Ledra aurita they are flat, and repre-
sent ears in some species of Tingis ( T. Echii, Pyri, &c.)
a kind of reticulated hood, resembling lace, is elevated
from the anterior part of the prothorax, which receives
and shelters the head In Centrotus globularis and cla-
vatus F., especially the former, thepartm question is armed
by a most smgular and wonderful apparatus of balls and
spines, — in one case standing erect and in the other be-
ing horizontal ^— which gives these animals a most extra-
ordinary appearance. In many of the species here quoted

See above, p. 327—.

Coquebert lUustr. Ic.W.t.xvm.f. 2, 4.

StoU Cigales L xxi./. 116. d Ibid. t. xi./. 5.3.

„ ^- ' Pi-ATE XIII. Fig. 18. «.

' btoll Cigales t. xxviii./. 163.

" Ibid. I. xxi./. 115. Coquebert lUusf. Ic. ii. t. xviii./. 5.

538 EXTERNAL ANATOMY OF INSECTS.

the prothorax is producted posteriorly into a long scu-
telliform horizontal horn, which more or less covers the
wings and abdomen ; a circumstance which also distin-
guishes the genus Acrydium F. {Tetrix Latr.). This
horn seems to have been sometimes regarded by Lmne
and Fabricius as a real scutellum, and sometimes only as
a process of the prothorax: but that it is merely the
latter will be evident to you, if you examine carefuUy
any insect furnished with this appendage; for if you re-
move that part, you will discover the true scutellum and
other parts of the trunk concealed beneath it. A very re-
markable prothoracic appendage is exliibited by some
species of Mantis. In general the part we are treatmg
of in this tribe is very slender ; but in M. strwnana, gon-
gyloides, &c., it appears dilated to a vast width, and as-
. sumes, either partially or generally, a subrhomboidal
form; but if it is more closely exaanined, it will be found
that the form of the prothorax is really shnilar to that of
the rest of the tribe, but that this part is furmshed on
each side, either on its whole length or anteriorly, with a
large membranous flat subtriangular appendage resem-
bling parchmenta. Perhaps this kind of sail may be useful
to the animal in flight. In Prioms corianus &c.. its sides
arearmed withteeth, and in m^x^y Lamice, Cerambyces^^^
other Capricorn beetles, and often in various bugs {Feiv
tatoma Latr.) with sharp fixed spines. But the protl^o-
raxh^s moveable as well ^ f^ed appendages; of this
kind are those spines {umhones\ whose base is a spheri-
cal boss moving'in an acetabulum of the thoracic sh.
of the Capricorn subgenus Macropus Thunb. If I might

Stoll

Spectres L xi./ 43. L xii./ 45. L xvi./ 58, 59.

EXTERNAL ANATOMY OF INSECTS.

539

hazard a conjectui'e, I should say that these organs were
given to this animal by an all-provident Creator, to en-
able it to push itself forward, when in the heart of some
tree it emerges from the pupa, that it may escape from
its confinement Another kind of moveable appendages
are attached to the thorax of Lepidoptera, usually in the
form of a pair of concavo-convex scales covered exter-
nally with a tuft of hairs ^. M. Chabrier, who examined
these scales in recent insects, describes them as vesicles,
which appeared to him frill of a liquid and of air, and ca-
pable of being alternately inflated and rendered flaccid ;,
he regards them as accessories to a pair of spiracles,
which he looks upon as vocal ^, opening into the mani-
trunk just above the insertion of the arms. These or-
gans are quite distinct from the tegulce that cover the
base of the primary wings of insects of this Order and
are what, borrowing a term from Moufiet I have called
in the table patagia, or tippets. Under this head I may
include the canmcles at the anterior angles of the pro-
thorax of a genus of beetles with soft elytra, named by
Fabricius Malachius. When pressed, says De Geer
of these insects, a red inflated soft vesicle, of an irregu-
lar shape, and consisting of three lobes, emerges from
the thorax and from each side of the anterior part of the
abdomen, which re-enters the body when the pressure is
removed M. LatreiUe seems to think that these vesi-
cles have some analogy with the poisers of Diptera and

- Plate IX. Fig. 4.

^ Sur le Vol dcs Ins. c. vii. 374. i. xviii./. 9. i i.

Plate IX. Fig. .5. " JVicftlr. Ins. 98.

' De Geer iv. 74.

540 EXTERNAL ANA'l'OMY OF INSECTS.

the pectens of scorpions; and that they are connected
with the respiration ^ ^

4. We are next to say someth'ing upon the shaj^e of
the fvothorax. The forms of the thoracic shield, espe-
cially in the Coleoptera, are so various, that it would be
endless to aim at particularizing all; but it may be use-
ful to notice a few of the most remarkable. The pro-
thorax of Moluris, a darkling-beetle, approaches the
nearest of that of any insect to a spherical form, from its
remarkable convexity; in the v^]^^e\-hng [Beduvius ser-
ratus) it is compressed, and longitudinally elevated mto
a semicircular serrated crest: it is crested, also, in many
LocustcB and Acridce, in some having two paraUel ridges;
but, generally speaking, its surface is more depressed.
In Necrodes it is nearly circular, in Blatta petivenana
semicircular, in Nilion and some CoccinellidcE crescent-
shaped, in Carahus obcordate, in Cantharis and Sagra
approaching to a square, in Languria to a parallelogram ;
in many Cimicidce. Belostoma, &c., it is triangular, with
the vertex truncated; it is trapezoidal in Elater, m Ateu-
chus rather pentagonal, and exhibiting an approach to
six angles in some other beetles'': but the prothorax
most singular in form is that of some species of M. La-
treiUe's- genus Helceus % as H. perforatus, Bromm, &c. :
in these its anterior angles are- producted, and curvmg
inwards, lap at the end one over the other, so as to form
a circular orifice for the head, which otherwise would be

» Organisation ExtSrieure des Ins. 177- ^.
^ A subgenus, related to Lcbm {Hexa^onm K. MS.) and some C.
micidtB, are so circumstanced.
Regne Animal Hi. t. xiii./. 6.

EXTERNAL ANATOMY OF INSECTS. 541

quite covered by the shield. Thus the upper portion of
the eyes can see objects above, as well as their lower por-
tion those below. I might enumerate many other forms,
but these are sufficient to give you some notion of the
variations of this part.

5. The ■prothorax is equally various in its sculpture ;
but since in the Orismological table almost every instance
of it has its place, I shall here only notice it as far as it
is common to the whole tribes, genera, or subgenera.
The ScarabcBicUe of Mr. W. S. MacLeay are distin-
guished by a small excavation on each side of this part,
which, as has been before remarked furnishes an ele-
vated base for an internal process with which the ante-
rior coxcB ginglymate. In Onitis and Phancsus, to these
excavations are superadded a pair impressed in the base
of the prothorax, just above the scutellum ; in Carabus L.
a longitudinal channel divides the thoracic shield into
two equal portions ; arid many genera of that great tribe
have in addition, at the base on each side, one or two
excavations or short furrows. Elophortis F. has on this
part several longitudinal channels, alternately straight
and undulated. Generally speaking, in Carabus L. the
prothorax has no impressed points ; but in one or two sub-
genera of Harpalida {Chlcenia &c.) it is thickly covered
with them. In numbers of Locusta Leach, the part we
are considering is what Linne terms cruciate^ being di-
vided into four longitudinal portions by three elevated
lines, the intermediate one being straight, and the late-
ral ones diverging from it both at their base and apex, so
as to form a sinus or angle''. In certain Acridce K.

* See above, p. .'W8.

" Plate XIII. Fig. 17.

542 EXTERNAL ANATOMY OF INSECTS.

{Locusta F.) there are only two of these lines or ridges,
but notched or toothed; and in some of the genus first
named only one in Locusta Dux and affinities the^jro-
thorax has several transverse channels or rather folds %
with corresponding ridges on its internal surface.

6. With respect to the clotJmig oH\i&prothorax, I have
not much to say : in Coleopterous insects this part is com-
monly naked; but in some genera, as Byrrhus, Anthrenus,
Dermestes, and many weevils {Curculio L.) it is partially
or totally covered with hairs or scales. In the other tho-
racic Orders it is usually naked, but in some Nmroptera,
the Myrmeleonina, &c., it is hairy; and in the Libellulina
it is fringed posteriorly with hairs.

7. As to its relative projjortmis, the prothwax is some-
times rather wider than the rest of the trunk and the
head, as in Onitis, Pasimachus, &c.; it is considerably nar-
rower in CollT/uris and OdacantJia; and of the same width
in those Scaritidce with striated elytra Again, it is
sometimes of the same width with the elytra, but wider
than the head, as In HydrophUus, Di/tiscus, &c.; in some
instances it is of the same width with the head, and nar-
rower than the elytra, for instance in A7ithia and Bra-
chinus. In most Coleoptera it is longer than tiie head
and shorter than the elytra; but in Manticora, the vesi-
catory beetles, &c., it is shorter than either. In Gnoma
longicollis\ it is nearly as long as the elytra; in many
Staphylinida, Afractocerus, Sec, longer; in PJianaus car-
nifexl bellicosus, &c., it is longer than the elytra and die
rest of the body. With regard to itself, it is sometimes

a Plate VIII. Fig. 10.

" Linn. Trans, vlt.wlf- 10.

" Ibid.
d md.f. 8.

EXTERNAL ANATOMY OF INSECTS.

543

very wide in proportion to its length — Dytiscus, Helceus;
at others very long in proportion to its width — CoUinrisy
Brenfiis, Mantis, &c. In Plata, and many other Ho-
mopterous Hemiptera, it is extremely short ; extremely
long in Gnoma ; in Sagra and Donacia its width about
equals its length ; in Elater, Dytiscus, and many Hete-
ropterous Hemiptera, it is narrowest before ; in Langu-
ria it is every where of equal width ; in Anthia, Carabus,
&c., it is widest before ; and, lastly, in the Scarabceidce
MacLeay it is usually widest in the middle.

ii. Antepectus^. — The antepectus, as was before ob-
served'', in some tribes forms one piece, without any
kind of separation, with the pirotliorax ; but veiy often
this is not the case. In Carahis L. it occupies almost
the whole under-side of the manitrunk ; but in Elatei;
in which the ora is very wide, the antepectus is merely
the middle portion of that part. In Carabus F. &c. be-
tween the ora and the base of the arms is a convex tri-
angular piece, distinguished from the rest of the ante-
pectus by a spurious suture ; and in Pentatoma and other
Heteropterous Hemiptera a similar piece is observable,
which terminates in a convex bilobed subtriangular
sheath, receiving the base of the clavicle This piece
seems a prop to that part, and analogous to the scapula
of tlie medipectus and parapleura of the postpectus. I
shall say no more upon the antepectus, as it is seldom
remarkable. In the mole-cricket, however, one peculia-
rity distinguishes it: it is in this of an elastic leathery

» Plate VIII. i. See above, p. 53G.

Something of the kind is observable at the base of the other
legs in this tribe.

544

EXTERNAL ANATOMY OF INSECTS.

substance, while the prostamum is hard, resembhng h
bone. In other insUnces these parts are both of tlie
same substance.

1. The sternum or breast-bone of insects consists
mostly of three distinct pieces ; in this resembling the
human sternum, which is described by anatomists as
composed originally of three bones Each of these
pieces is appropriated to a pair of legs, and each of them
at times has been called the sternum : thus in Elater the
prosternum, in the Cetoniadce the mesosternum, and in i^-
drophilus the metasternum, have been distinguished by this
name. Our business is now with the first of these pieces,
the sternum of the antepectus or prosternum^: this is the
middle longitudinal ridge ofthefore-breast, which passes
between the arms, when elevated, extended, or otherwise
remarkable. It is most important in the Coleoptera Or-
der, to which my remarks upon it will be chiefly con-
fined. In these it is sometimes an elevation, and some-
times a horizontal process of the fore-breast. If you
examine the great Hydrophilus {H. piceus), at first you
wUl think that there is only a single sternum common to
all the legs; but if you look more closely, you will per-
ceive between the head and the arms a triangular vertical
process, with a longitudinal cavity on its posterior face,
which receives the point of the mesosternum that passes
between the arms- this vertical piece is the real pro-
sternum, and not the other, which really belongs to tlie
alitrunk. In this case the elevation of the prostermim is
before the arms; in others it is between them, as you

>. Monro On the Bones, 160. " Pi-ate VIII. d' .

= Ibid Fig. 7. d'.

EXTERNAL ANATOMY OF INSECTS.

5-1.5

may see in a Chinese chafer {Mimela K.), which imi-
tates the external appearance of a (juite different tribe^* ;
in others again it is behind them, as in most of the Lamel-
licorn beetles. In the common dung-chafer (Geotrupes
stercorarim), it is a hairy process, which, when the head
is bent downwards, is received by a deep cavity of the
mesostermum. The DynastidcE MacLeay may always
be known by a columnar prosternum rising vertically be-
tween the arms and the medipectus. Lastly, in other
tribes there is a prosternal elevation both befoi e and be-
hind the arms, as in Cerambyx thoracicns, dimidiatus^ and
affinities. Of the second description, those that have a
less elevated horizontal prosternum^ the point in most is
to the anus^ but in some to the head : thus in Carabus L.
it is generally a subspathulate flat piece, the point of
which slides over the mesostermm, or covers it ; but in
Harpalus megatephalus Latr. ^, one of this tribe, though
similarly shaped, its point is to the head. These hori-
zontal prosterna vary in their termination. In that of
Carabus L. the apex is obtuse; in that of Elater, above
described S and Dytiscus it is amtc; in Prio7ius lineatus,
Spencii K., &c., it is bilobed; and in Buprestis variabilis^
attenuafa, &c., obsoletely trilobed. With regard to the
other Orders no striking features of this part are observ-
able, except in some Orthoptera. In Acrida viridissima
K. {Locusta F.) it is represented by two long filiform ver-
tical processes ; and in Locusta Leach by a single coni-
cal horn 'I, mistaken by Lichtenstein for a process of the

" Kirby in Linn. Tram. xiv. t. m.f. 4.1

" It IS doubtful whether M. Latreille's Harpalus viegncephalus is
synonymous with Carabtis viegacephalm Fab. Comp. Gni. trust, et
Ins. \. 206. with Sysf. Eleiith. i. 187. 95.

' Vol. II. p. 317—. J Plate VIII. Fig. 11. h.

VOL. in. 2 N

546 EXTERNAL ANATOMY OF INSECTS.

throat \ In one instance, Gryllotalpa, this part is a long
piece between the arms, shaped Uke the human thigh-
bone or ma, being more slender in the middle and
widest at the ends, and which is of a much hai-der sub-
stance than the rest of the antepectus, and forms the
lower termination of a singular nmchine which will be-
fore loner be noticed. In many bugs {Cimicidce), mstead
of being elevated, the three portions of the sternum are
hollowed out into a longitudinal groove, m which the
vromuscis when unemployed reposes.

The most conspicuous and remarkable appendages ot
the manitrunk, are the brachia or arms. I shall not,
however, enter into the full consideration of these, as they
consist numerically of the same parts, till I treat of the
le^s in creneral. Here it will only be necessary to assign
my reasons for calling them by a distinct denomination.
In this I think I am authorized, not only by the example
of Linne, who occasionally found it necessary to do this ,
and more particularly by the ancient notion that this
pair of organs in insects were not to be reckoned as legs ,
but likewise from their different position and functions.
They are so inserted'in the antepectus as to pomt towards
the lead, whereas the other two pair point to the anus
With regard to their functions, besides bemg ambula-
■ ,or,, and supporting the manitrunk in walking, ^h^^^^^
appHed to many other purposes independent of ha of-
fice-thus they are eminently the .can.o;^/ or clmibmg
le.s in almost all insects; in most Carabi L., by means

, . ^ , W 53 " S-ust. Nat. i. Cancer. Scorpio.

dently considers the antenor pan-as«rm, Bochart uo
Levif. %\. 20-. Hierozoic. n. 49/ .

EXTERNAL ANATOMY OF INSECTS. 547

of the notcli and calcar they are prehensoi-y legs ; in
Scarites belonging to that tribe, the Lamellicorn beetles,
and the mole-cricket, they are fossorious legs, or proper
for digging"; in Mantis, Nepa, and some Diptera, they
are raptorious, or fitted to seize and dispatch their prey<=:
they ave used also by many insects to clean their head,
eyes, and antennae, &c. For many of these purposes
they cannot be fit without a structure different from that
of the other legs, which renders it a matter of as great
convenience in descriptions to speak of them and their
parts under different names from those of the legs, as it
is of the arms of man ; on this account it is that I propose
to give to the fore-leg and its part the names by which
the analogous parts, or what are so esteemed, in the hu-
man species are distuiguished;— when spoken of in com-
mon with. the other legs, diey may still be called the fore-
legs. «

* * Alitntncus. The alitrunk is the posterior segment
of the trunk, which below bears the four true legs, and
above the organs for flight or their representatives. In
treating of this part we may consider its insertion or ar-
ticulation, its shape, composition, substance, motions, and
07-gans.

i. With regard to its insertion, or articulation with the
manitrunk and abdomen, it may be observed that it is
attached to both by its whole circumference by means of
ligament; in the Coleoptera, Orthoptera, and Heteropte-
rous Hemiptera being received by the posterior cavity of
the prothorax, the shield of which in these Orders, espe-

» Plate XXVII. Fig. 31. b p^.^^^. xv. Fig. 5, 6.

' Satnoiielle t. v. /. 4.

2 N 2

548 EXTERNAL ANATOMY OF INSECTS.

daily the last, almost covers and conceals it; but in the
remaining ones it is merely suspended to it. In the
former also, especially in the Coleoptera, it seems more
separate and distinct from the manitrunk than from
the abdomen, and more independent of its motions
than of those of the latter part: but in the Hi/?neno-
ptera and Diptera its greatest separation is from the
abdomen in both respects. In many insects, as in the
Lamellicorn beedes, the mole-cricket, &c., the mani-
trunJt terminates posteriorly, drawing a line from the
base of the protJiorax to the antepectus, in an oblique
section; in other tribes, as in the Cei'amhyx L., the
Predaceous beetles, &c., the section here is ofteji vertical,
but in the alitrunk the anterior one is always verti-
cal, while the posterior, by which it articulates with the
abdomen, in the Orders with an ample thoracic shield, is
oblique, so that the pectoral portion is more ample than
the dorsal.

ii. As to its composition, the alitrunk is usually much
more complex than the manitrunk ; for, besides the in-
strmnents of motion, it consists of numerous pieces. It
maybe regarded as formed o^two greater segments, the
first bearing "he elytra, or the primary wings, and the
mtermediate legs ; and the second, the secondary wmgs

and the hind legs.

1. Collare \ The first segment of the ahtrunk is the
middle piece of the whole trunk, and therefore, when
spoken of per se, may be called the meditnmais. It
consists primarily of an upper and lower part, which
in the table are denominated the mesothorax and the

» Plate IX. g.

EXTERNAL ANATOMY OF INSECTS.

549

inedipectus. The first piece in the former that requires
notice is the collar. I formerly regarded this piece,
which is pecuhar to the Hymenoptera, Diptera, and one
tribe of the Neuroptera, as the representative of the pro-
thorax in the other Orders, and this opinion seems at this
time very generally adopted, but subsequent observa-
tions have caused me to entertain considerable doubts
of its correctness. Many other Entomologists have
thought it improper to distinguish these parts by the
same name^ Much, however, may be said on both
sides of this question, and I shall now lay before you the
principal arguments that may be adduced in defence of
each opinion, beginning with Nthose that seem to prove
that the collar is the analogue of the prothorax. First,
then, the collar, like the prothwax, is placed precisely
over the antepectus, and being placed in the same situa^
tion, on that account seems entitled to the same denomina-
tion ; especially as in some genera, for instance Chlorion
F., it assumes the very semblance and magnitude of a
thoracic shield, and is separated from the mesothorax by
a considerable incisure. Agam, in some cases that have
fallen under my own observation, the collar is endued
with some degree of motion distinct from that of the
alitrunk, smce in Pompilus and Chrysis the animal can
make the former slide over the latter in a small degree.
A thu-d and last argument is, that no prophragm is
formed from the collar : insects that have a thoracic shield
are generally distinguished by having the anterior margin
of the dorsolum deflexed so as to form a sephm, called in

» LatreiUe Organization &c., 199. Chabrier Sur U Vol des Im.
c. 1. 412. c. IV. 54, &c.

550 EXTERNAL ANATOMY OF INSECTS.

the table the p'ophragm, which enters the chest and se-
parates the cavity of the mesothorax from that of the pro-
thorax ; now in Hymenoptera this septum is a process
of the' piece behind the collar, and excludes it from
having any share in that cavity. These arguments al.
lirst sight seem to prove satisfactorily the identity of the
collar 'and prothorax. But audi alteram partem, and I
think you will allow that the scale containing the claims
of the collar to be considered as a piece sui generis, dips
much the lowest. And, first, I must observe, that
though in Hymenoptera the collar seems to replace the
prothorax by its situation, yet it is in fact a part of the
alitrunk ; for, if the manitrunk be separated from the lat-
ter, the collar remains, in most cases, attached to it%
while t\i^antepecttis and arm, with the ligamentthat covers
its cavity above, the real representative of the prothorax,
are easily removed, and this in recent individuals: as a
further proof of this, I must request you will examme a
neuter MutUla; you will see that in this the collar is
not separated from the alitrunk in any respect, but forms
one piece with it, whUe the antepectus is distinct and
capable of separate motion : further, the action of the
collar is upon the alitrunk, it being of essential import-
ance in flight, whereas the prothorax is of no other im-
portance than as a counterpoise to that part''. A further
argument to prove the distinction of these parts may be
drtwn from the case of Xylocopa, a kind of bee. In this
genus the collar forms a complete annidus or segment oi

a In Chlorwn, AmnwpMla, &c., this part separates more readily

from the alitrunk. . . . .1 ^_

^ Chabrier Snr Ic Vol dcs Ins. c. i. 413- c. iv. o4. Thi author
seems to regard the collar as something peculiar to Hymcnoplcra.

EXTERNAL ANATOMY OF INSECTS. 551

the body : now, if it really represented the prothorax,
the under side of the segment, as in those Coleoptera in
which no suture separates the upper from the lower part
of the manitrunkS should represent the flw/ej^ec/w^, and
have the arras inserted in it; but in the case before
us diere is a distinct antepechis bearing the arms received
by the socket fonned by this annulus. But the most
powerful argument is the fact that some insects have
both the prothorax and collar, a circumstance tliat com-
pletely does away every idea of their identity. If you
examine the common hornet {Vespa Crabro\ or any
saw-fly {Tenthredo L.), you will find, as was before inti-
mated, that the real covering of the cavity of the mani-
trunk is a ligamentous membrane, which properly re-
presents the protJiorax. In another genus of the same
order {Xiphydria Latr.), the sides of the antepectus turn
upwards and nearly form a horny covermg distinct from
the collar ^ the hgamentous part being reduced to a
very narrow line, and in Fcejizis the dorsal fissure is quite
filled up, so that in this the manitrmik is perfectly di-
stmct, and exhibits hdth prothorax and antepectus of the
usual substance. In Nomada likewise, N. Goodeniana K.
was the species I examined, there is a short minute pro-
thorax besides the collar. Next let us turn our attention
to the Diptera ; if you examine the common crane-fly
( Tipzila oleracea), you will find, first, a regular short
prothorax, to which the antepectus, with the arms, is at-
tached ; and behind this also is a short collar embracing
the alitrunk anteriorly. The next insects that I shall
mention, as exhibiting both prothorax and collar, are the

See above, p. 536.

" Pi. viF IX. Fjg. 14.

EXTERNAL ANATOMY OF INSECTS.

LibelluUna, These are generally admitted to have the
former of these parts % but besides this they have also
the latter, which is the most ample and conspicuous
piece in the whole trunk intervening, as the collar
should do, between the prothorax and those parts of the
trunk to which the wings are attached. There is one
circumstance connected with the subject which should
not be overlooked. In the Hymenoptera, usually under
a lateral process of the posterior part of the collar, is a
spiracle or respiratory apparatus; m ihe Diptera t\veve
is also one, though not covered by the part in question,
in the same situation ; now this you will find precisely so
situated with respect to the second piece in the thorax
of Tipula oleracea, proving that this piece is the real re-
presentative of the collar. Enough, I think, has been
said to satisfy you that I have not changed my senti-
ments on this subject upon slight grounds. Probably
traces of the part in question might be detected m the
thoracic Orders in general, in connexion with some
vocal or respiratory organ but having had no oppor-

a Plate IX. Fig. 6. a. ». Ibid. Fig. 7- g •

c M Chabrier ( Vol. des Ins.) supposes that the Immmmg of insects
is produced by the exit of the superfluous air from their thoracic
Piracies, &c. - in Melolontha he thinks they are in the vMorax nn-
r he win s (c. i. 457- P.a.e XXII. Fig. 13. c. f. represents the
opercrduJi one of those of Dytiscus ,««.gi,^«/«) : m tl- -^i'--
Zera, in the mesothora,, near the posterior lobes of the colla. (Ibid
459. c. iv. 50.); and in the mptcra, in the ,».^«^AoW near the
noLr (c i 457 ). I observed myself lately, that Ehplnlus teuax,
rhe d by' the anterior part of the body, when it hummed, alter-
ately opened and shut this spiracle. The wings dunng the sound
vibrtLd'intensely. The hum ceased and was renewed, as they we e
rS ained from this motion or released from restraint; when the
wtg moved towards the bend, a different sound was emitted trom
tliat'^l)r()duced when it iiu-rcly vibrated.

EXTEnNAL ANATOMY OF INSECTS.

555

tunity, by an extended examination of living subjects, to
verify or disprove this suspicion, I shall merely mention
it, and conclude this head by observing, that the collar
varies most in the Hymenoptera order, and that its most
remarkable form is in Vespa^ Cimbex, Dm-ylus, &c., in
which it bends into an ample sinus that receives the
dorsolum''.

2. Dorsolim^. AVhere there is no apparent collar,
the dorsolum (dorslet) is thej^r5^ piece of the mesothoraxi
and where there is one, the second; it bears the elytra
or other primary organs of flight. It varies in the dif-
ferent Orders, particularly with respect to its exposure.
In Coleopterous insects it is most commonly, but not
invariably % covered entirely by the shield of the protho-
rax, the scutellum alone being visible; as it is also
in the Orthoptera (with the exception of Mantis and
Phasma, in the first of which it is partially, and in the
latter intirely exposed), and the Heteropterous, and
most of the Homopterous section of the Hemiptera.
The scutellum is hkewise covered in Gerris, Hydrovie-
tra, and Velia, and the whole of the back of the alitrunk
by a process of the protliorax in Acrydium F., Centro-
tics, &c. But in the remaining Orders, and the tribe
of Tettigonia in the Homoptei'ous Hemiptera, the dor-
solum is not hidden by the thoracic shield. It is usually
less elevated than the scutellum; in Nea-ophorus, and
some other beetles, however, the latter is most depressed.
With regard to its substance, it is generally not so hard

\ Plate IX. Fig. 11. g'. b plates VIII. IX. i'.

" When the protkorax is separated from the elytra by a kind of
isthmus, as in Scarites, Pasmlus, &c., tlie dorsolum is more or less
uncovered.

554' EXTERNAL ANATOMY OF INSECTS.

and rigid as the scutellum, but in most Coleoptera harder
than in the other Orders in which it is covered ; in
the Hemiptcra, except in Tettigonia, it approaches to
membrane. As to shape and other circumstances, it
varies in the different Orders. In the beetle tribes it
has generally a sinus taken out of its anterior margin,
and it approaches more or less to a trapezium ; in Blatta
It is transverse and somewhat arched; in Gryllotalpa it
is nearly square, and distinguished besides on each side
by a minute aperture, fitted with a tense membrane,
which perhaps covers a respiratory apparatus. In the
locusts it is more or less triangular, and in Mantis and
Phasma long and slender. In the Hemiptera the dorso-
lum appears to consist of several pieces, variously cir-
cumstanced, separated by sutures, corresponding with
which are as many ridges on the inside ot the crust ^
In the LibeUulina it is rhomboidaP; in Panorpa nearly
hexao-onal; in the Ephemerina it is ample and oblong;
in SUtlis and the Trichoptera this part is represented by
three subtriangular pieces, the saUemm constituUng a
fourth, with the vertices of the triangles meeting m the
centre <=; in the Lepidoptera the part in question is large,
and receives the scutellwn into its posterior sinus ^. 1 he
Hymenoptera usually exhibit a very ample dorsohm,
mostly subtriangular with the vertex rounded or trun-
cated, and pointing in some (Vcspa L.) to the head ,
^nd in others {Apis) to the anus ; in theDiptera, except in
Tiptda, the parts of the mesothorax are not separated by
any suture, but only indicated by impressed lines or chan-

" .P...KVin.Fio.i6.20.i'.

. , xV in ■' /.' Ibid. tlG. 1. ? . A .

Ibid. Fig. 10. » . •

0 Ibul. Fig. U. i' •

EXTERNAL ANATOMY OF INSECTS. 555

nels ; in the genus last mentioned, however, tlie dorso-
lum is distinct, subrhomboidal, and received by an angu-
lar sinus of the scutellum, which last, I think, is not the
part that has usually been regarded as entitled to that
denomination ; for this opinion I shall soon assign my
reasons.

3. SciUellim ^. Some writers on the anatomy of in-
sects, looking, it should seem, only at the Coleojptera and
Ortlioptera, have regarded the dorsolum and scutellum as
forming only one piece ^ and others have affirmed that
the Lepidoptera and subsequent Orders have no scutel-
lum'^. But as we proceed in considering the scutellum
in all the Orders, we shall see that both these opinions
are founded on partial -vnews of the subject, and that all
Avinged insects have a saitellum, more or less distinctly
marked out or separated from the dorsolum. In the Co-
leoptera the scutellum is usually the visible, mostly trian-
gular, piece that intervenes between the elytra at their
base'^, and which terminates the dorsolum. SomeLamel-
licorn beetles, &c. [Scarabceida MacLeay) are stated not
to have the part in question {exsaitellati): but this is not
strictly correct, for in these cases the scutellum exists as the
point of the dorsolum covered by the prothorax, though
it does not intervene between the elytra: in others of
this tribe, as Cetonia chinensis, bajtda, &c., it separates
these organs at their base, though it is covered by the
posterior lobe of the protJiorax: in Meloe F., the elytra

Plates VIII. IX. XXVIII. Audoin, Chabrier, &c.

Olivier. He seems also to have thought that neither the Or-
tkoptera nor Homopterous Hnnipicra have this part. N. Did.
(VHlit. Nat. X. 112.

Plate VIII. Fig. 3. k'.

556 EXTERNAL ANATOMY OF INSECTS.

of which are immoveable, there seems really to be no
scutellum. Generally speaking, as was lately observed,
but not always, it is distinguished from the dorsolum by
being more elevated: this is particularly conspicuous in
the genus Elater, in which it is a flat plate elevated
from the dmsolum by a pedicle; in Sagra the latter part
is horizontal, while the scutellum is vertical: and even in
cases where the distinction is not so striking, these parts
are separated either by a line, or some difference in their
sculpture and substance. In this Order this part varies
greatly, and often in the same tribe or genus, both
in size and shape ; being sometimes very large % and
sometimes very minute; sometimes very long, and some-
times very short; sometimes nearly round, at others
square; now oval or ovate, heart-shaped, triangular,
acuminate, intire, bifid, &c. In the Orthoptera, though
less conspicuous, it still is present as a triangular eleva-
tion of the middle of the posterior part of the dorsolum,
with the vertex either pointing towards the head, as m
Blatta, or towards the tail, as in Locusta Leach ^ In
the Heteropterous section of the Hemiptera (which, m
columns of Mandibulata and Haustellata, appear to bear
the same reference tp the Coleoptera, th^t the H^meno-
ptera do to the Diptera, and the Homopterous Heini-
ptera to the Orthoptera^) the part we are considering is
mostly very large and conspicuous, quite distinct fi'om the

a In Macrasfis MacLeay it is often half as big as an elytrum.
b Plate VIir.FiG.12.A;'. u n n t. n

c Mr W. S. MacLeay opposes the llemxj>lcra to the Orthoptaa,
the Homoptera to the Ncuroptera, and the Aptera to the Coleoptera:
but if analogous structure be made the gmde I thmk my arrange-
ment will be found most correct. Hor. Entomolog. 367.

EXTERNAL ANATOMY OF INSECTS.

557

dorsolum, and in some [Tetyra F.) covering the whole
abdomen, as well as the Hemelytra and the wings ; it is
most commonly, as in the Coleoptera, obtriangular^, but
in the last-mentioned genus it often approaches to a pen-
tagonal shape. Though usually so striking a feature in
this tribe, in the aquatic bugs {Gerris &c.) it is covered
by the protJiorax. In some species of Reduvius F. ( R.
bigtittattis, mutillarius, higens, &c.) it is armed with one
or more dorsal or terminal spines. In the Homopterous
section, where the dorsolum, as in Tettigonia F., is not
covered by the prothorax, the scutellum, which is merely
a continuation of that part, bears some resemblance to a
St. Andrew's cross, and terminates in a fork''; in Ful-
gora, in which it is partly covered, it is merely the trian-
gular point of the dorsolum; in the Cercopidce, &c., whose
dorsolum is wholly covered, the triangular scutellum is
distinct from it ; in Centrotus, Daimis, and Membracis, in
which the prothorax is producted, and covers the abdo-
men more or less, the scutellum is a short transvei'se di-
stinct piece. In the Lepidoptera, from the difficulty of
abrading sufficiently the scales and hairs without injuiy,
it is difficult to obtain a correct idea of the part in ques-
tion ; in the cabbage butterfly {Pieris Brassicce) it ap-
pears to be triangular: in the humming-bird hawk-
moth {Macro-glossum Stellatarum) it approaches to a
rhomboidal shape <=; and in the eggar-moth {Lasiocampa
Quercus) it is completely rhomboidal. In the Libellu-
hna, in the Neuroptera Order, it seems to be represented
by the posterior point of the dorsolum, which terminates

» Plate VIII. Fig. 20 k' . h Ibid. Fig. 16. k' .

<■■ Pi.ATii IX. Fig. 1. k'. N. B. This is from Cossus F.

558 hxteHnal anatomy of insects.

in something like a St. Andrew's cross ^ In most of
the other tribes of this Order the scutellum is a triangu-
lar piece, with the vertex to the head, received between
two pieces of the dorsolum; m Psocus it is nearly like
that of Tettigonia before described. In the Hi/meno-
ptera the scutellum is separated from the dorsolum, which
it often embraces posteriorly, as the collar does in front,
by a suture ; it varies occasionally in shape in the diffe-
rent tribes, most commonly it is crescent-shaped, but in
many Ichneumonida and others it is triangular in the
hive bee, &c., it overhangs the succeeding piece of the
alitrunk; in Melecta, Crocisa, &c., it is armed with a pair
of sharp teeth in others {Oxyhelus uniglumis, &c,) with
one or more spines, and in some with a pair of long
horns''. Before I describe this part in the Diptera, it
will be proper to assign my reasons for considering a
different piece as its representative, from what has usually
been regarded as such, and which^ at first sight seems
the analogue of what I admit to be the scutellum in the
Hymenoptera. The dnrsolum, and its concomitant the
smtellum, belong to the first pair of the organs of flight,
which are planted usually under the sides of the former,
and m the case oimngs, by their Anal Area, connected
either mediately or immediately with the latter. Now, if
you trace the sides of the piece that I have considered as
the part in question in Hymenoptera, you will find that
they lead you not to the base of the lo'wer but to that of
the upper wings'^, and in the saw-flies [Tenthredo L.)

«P.ATElX.FlG.7./.'. Mbid.FiG.11,15.//.

Mon. Ap. Angl. i. t. vi. Apis. ** a./. 2. na.

StoU Cigales t. xxviii. /. 164.
« Platf. IX. Fig. 12. I:'.

EXTERNAL AN-iTOMY OF INSECTS. 559

you will see clearly that the Anal Area of these wings is
attached to a process of it, a proof tliat it belongs to the
mesothorax, or region of that pair. But in the JDipiera,
the part that has been usually called the smtellim is not
at all connected, either by situation or as a point of at-
tachment, with the wing itself, but with the lower valve of
the alula, which is with reason thought to be the repre-
sentative of the secondary wing of the tetrapterous Orders.
You may see this even in the common crane-fly ( Ti^ula\
in which there is a real alula^ connected by means of a la-
teral process, terminating in ligament, with this supposed
smtellum. If you examine further the same insect, you
will easily find what I regard as the true one in the bi-
lobed piece which receives the dorsolum, situated be-
tween the wings, and to the sides of which they are at-
tached. In Asilus, Tahanus, &c., this part is transverse,
and only distinguished on each side by an oblique im-
pressed line ; in the MuscicUe it is square, and marked by
a straight transverse one.

4. Frcenum ^ This appendage to tlie scutellim and
dorsolum varies considerably in the different Orders, and
in many cases, as you will see, is a very important part,
being the process by which the former is mostly con-
nected with the elytra or upper wings. In the Coleo-
jptna, the elytra of which are nearly stationary in flight,
and therefore less require any counteraction to prevent
their dislocation, this part is commonly merely a process
or incrassation of the under margin of the scutellum,
which towards the base of the dorsolum is dilated to
form the socket for the elytra. Its use as a countercheck

» Plates VIII. IX. XXVIII.

560 EXTERNAL ANATOMY OF INSECTS.

in this Order is best exemplified in the common water-
beetle {Dytiscus marginalis). This at the inner base
of the elytra has a membranous fringed alula resembhng
those of Diptera; to the lower fold of this the extremity
o^ the frcemm is attached, which forms a right angle with
the scutellum, and the upper fold is attached to the base
of the elytrum \ The object of this appendage is pro-
bably to prevent the dislocation of these organs, which
seems to indicate that they are used more in flight than
those of other beetles. The Blatta also, in the next Or-
der, have a winglet attached to the anal area of the teg-
mina. Thefrcenum, as in the preceding Order, lies un-
der the margin of the scutellum and dorsolum, but which
here forms one uninterrupted transverse line ; it is near-
ly vertical, and is attached to the alula. The structm'e
is not very different in the other Orthoptera\ but the
frcenum is surmounted or strengthened by one or two
ridges; in Mantis it runs from the scutellum m an an-
gular or zigzag direction-but in all it is attached im-
mediately to the tegmen. In the Heteropterous Hcm^-
Vtera it is represented by the narrow bead adjacent to the
scutellum on each side S which dilates into a flat plate as
itapproachestheifm.Zymm,withtheAnalAreaofwhich

it is connected. Butthe Homopterous section of the Order
in question furnishes examples of the most remarkable
structure of this countercheck, which proves that it is real-
ly, what its name imports, a bridle. If you examine the
ieatlanthorn-fly {Fulgora laternaria), or any species of
\ettigonia, &c., you will find adjacent to the scutellum

aP..xKXXlII.Fi..6.."'. Plat. VIII. Fio. 12./'.

«= Ibid. Fig. 20. I.

JCXTERNAL ANATOMY OX' iNSFXTS. fjOl

or paj allel witli it, on e4u;li side a flat plaU; ; and from tJje
angle of timt part in the first case, and from one of its
pj-ocx'sses in the last, you will further perceive a ridge or
nervure which runs along this plate, in one forming an
angle, and iji the other l>eing nearly straight, to the base
of the leumm, where it becomes u niarginal nervure to a
nienibrane that in attached to the posterior part of the
base oj- the Anal and Costal Areas; and that this marginal
/iervure, like a trac/iea, amsists of a spiral thread, or
rather of a numlK-r of cartilaginous rings wmnected by
elastic membraijeS and consequently is cai)able of crm-
siderable tension and relaxation, as tha iegmen risc^ and
lalls in flight. In the Lepidoptera it appears to Imj a
•short piece overhung by the scut^illum, which as it ap-
proaches the base of the wing is dilated In the Libel-
tulina, Ui g(i u> the NeuropUra, it has the same kind of
elastic nervure connected with the Anal Area of the wing
wh/ch I have just described in the Homopterous Hemi-
pLuru; another nervure, in M,hna at least, appears U>
diverge upwards from the scutellar angle t^nhe Interme-
diate Area'': a structure little different distinguishes the
rest of the Neuroptera, and even the Tricfioptera. In the
Hymerwpta-a this part varies somewhat; in the majority
perha,)s of the Order, as well as in the Diptera, it ap-
pears to be merely the lateral termination of tl»e scutel-
lum where it joins the wing; but in some tribes, as in
lenlhredo L. (especially Per^ra Leach), Hirex L., and
tlie Ichnmmonidce, a ridge, and sometimes two, runs
Irom the scutellum to the wing; the upper one, where

' Plate XXVIII. Kic. Jl.if'

" Chabricr Sur U Vol dUt luz. c. iii. /. yiii_v B /

roL. irr. 2 o

562 EXTERNA!. ANATOMY OF INSECTS.

there are two, as in Perga, being the stoutest, and con-
necting with the Costal Area, and the lower one with the
Anal.

5. Pnystega \ We learn from M. Chabrier, that m
the * common dragon-fly, a space, consisting of three
triangles, which immediately succeeds the/rOT^ af-
fords attachment to no muscles, but merely covers aerial
vesicles b. This is the part I have called the piystega ^
An analogous piece may be discovered in Phasma and
Mantis in a similar situation; but I cannot trace it in
Lociista Leach, or in the other Orders.

Having considered the parts that constitute the meso-
thorax, we will next say something upon those, as far as
they require notice, that compose the medi^ectus or mid-
breast. But first I must observe in general of the me-
dipectus and postpectus taken together, or the whole un-
derside of the alitrunk, that though usually they are m
the same level with the antepedus or under side of the
manitrunic, yet in several instances, as the ScaM^
MacLeay, the Staphylinida;, &c. they are much more
elevated than that part; they are also usually longer,
very remarkably so in Atractocerus, but in Elater sul-
catus and many others they are shorter. These parts
are also commonly rather more elevated than the abdo-
men -much so in some, as Molorchus; but scarcely at all
in others, as Buprestis, the Heteropterous Hemtptera, &c.
In some of the latter {Tetyr a Y.) the abdomen seems
the most prominent. Another observation relatmg to

^ Plate IX. Fig. 7-

^ Chabrier Sur h Vol dcs Ins. c iii. 3o4.
e From -^vU, to breathe and Hyo to cover.

EXTERNAL ANATOMY OF INSECTS. 563

this part must not be omitted, namely, that though in
many cases the medipcctus and postpectus are perfectly
distinct and may be separated, yet in others, as for in-
stance the Lamellicorn beetles, the Hymenoptera and
Diptera, &c., no suture separates them; so that though
the upper parts, the mesothorax and metathorax^ are se-
parable, the lower ones just named are not so.

6. Peristethium The first piece of the medipectus is
what I have called, after Knoch, the peristethhnn^ . This
immediately follows the antepectus; on each side it is
limited by the scapulars, and behind by the mid-legs and
viesostenmm. Its antagonist above is usually the dorso-
lum. In the Coleoptera Order it varies occasionally,
both m form and magnitude, but not so as to merit par-
ticular notice, except that both are regulated by the sca-
pulars— if these are small, the peristethium \s ample; and,
vice versa, if they are large it is small. In all the fol-
lowmg Orders, except the Hymenoptera, it is equally
inconspicuous, but in them it is often more remarkable.
I have a Brazilian species of Cimbex (C. 7nammifera
K. MS.) which appears undescribed, in which this part
swells into two breast-like protuberances, terminating
posteriorly in membrane, as if it had separate motion : in
the golden-wasps {Chrysis L.) it is anteriorly concave to
receive the coxa of the mid-legs; and in Stilbuin, of the

Plates VIII. IX. ra'.
^ At first I had named this piece the antecosta, and the mesoste-
thtum the postcosta; and there is certainly some analogy between the
thorax of insects, consisting of several pieces that follow each other,
and the vertebral column ; between then- three sternums and the ster-
nmn, and between their other pieces and the ribs of vertebrate
animals. Comp. Chabrier, ubi supr. c. iv. 49. note 1.

2 o 2

564 INTERNAL ANATOMY OF INSFXTS.

same tribe, it is armed with one or more conical obtuse
teeth.

7. Scapularia*. The scapulars are situated between the
cox(E of the mid-legs and the base or axis of the upper
organs of flight, and they seem to act as a fulcrum to each.
In the Coleoptera Order they are most commonly qua-
drangular or subquadrangular, often divided diagonally,
and sometimes transversely, by an impressed line ; the
posterior part, which is usually the most elevated and
often has an uneven angular surface, is that which in-
tervenes between the coxae and elytra : where the former
are short, as in the Capricorn beetles, the scapulars are
long; and where they are long, as in the Petalocerous
one"^, the latter are short. The anterior part is that
which forms the lateral limit of the peristethium, upon
which it often encroaches: this part, in conjunction with
the dorsolum above, and the last-named part below,
forms the kind of rotula that plays in the posterior aceta-
bulum of the manitrunk, as the head does in the anterior
one. In the flower-chafers {Cetonia F.) the scapulars
are very thick and elevated, and interpose between the
posterior angles of the protJiorax and the shoulders of
the eli^tra, which is one of the distinguishing characters
of that tribe : in this case the lower angle of the scapular
connects with the coxa of the mid-leg, and the upper
angle with the axis of the and the most elevated

and thickest part of the scapular is about midway between
the two. This robust structure seems to indicate that
the scapular has to counteract a powerful action both of
the leg and elytrum. In the Or/hoptcra the scapulars

» Pr.ATES VIII. IX. o.

EXTERNAL ANATOMY OF INSECTS.

565

are usually divided into two parallel pieces, corresponding
probably, though more distinct, with the two parts late-
ly noticed of those of the Coleoptera : the upper side of
the socket of the mid-leg is common to the base of both
these pieces, but the articulation of the tegmen is chiefly
with the anterio}' one. In the grasshoppers, locusts, &c.
{Gryllus L.) in which tribe this leg is nearly opposite to
that part, the scapular inclines but little from a vertical
position*; but in the praying- insects [Mantis), spectres
{Phasma), and cockroaches {Blatta), in which the in-
sertion of the mid-legs is behind that of the tegmina, it is
nearly horizontal. In the Heteropterous Hemiptera the
anterior part of the scapular is covered by the antepectus,
and separated by a ridge, more or less pronounced, from
the open part ; the whole is of an irregular shape, and
nearly parallel with the faraplenra. In the Homopterous
section it likewise consists of two pieces, and sometimes
of more. Thus in Tettigonia F. it is bilobed, and be-
tween it and the coxa two small pieces are inserted''. In
some others, lassus Lanio F., &c., it is not very unlike
the scapular in Coleopta-a, being subquadrangular and
divided diagonally. In the Neur-optcra this part and the
parapleura are parallel, and placed obliquely In the
common dragon-fly [jEshna viatica) the former forms
nearly a parallelogram which is not divided by any
ridge or channel, but its lower half is separated into two
unequal parts by a black longitudinal line, opposed to
which on the inside is a ridge. The mid-leg in these is
connected with the scapular by the intervention of a

» Plate VIII. Fig. 12. 13. o'. z' .
^ Pl.me IX. Fig. 8. o . z .

*• Ibid. Fig. 17- o\
Ibid. o'.

56 6 EXTERNAL ANATOMY OF INSECTS.

triangular transverse anterior piece, which in fact seems
only marked by a black channel, to which also interiorly
a ridge is opposed ^ In the rest of the Order it is divided
longitudmally into two parallel pieces. In Panorpa the
posterior piece is longer than the anterior and props
the coxa behind ; in Myrmeleoji and Perla, &c., it ap-
pears to consist of three pieces. I have not been able to
obtain a clear idea of them in the Lejndopiera, except
that they have more than one piece. Hymeyiopterous
and Dipterous insects for the most part have no scapular
distinct from the peristethium ; but in Cimhex, Perga,
and other saw-flies, it seems represented by its posterior
depressed and sometimes membranous part : in V esp)a,
&c. a small subtriangular piece, just below the base of
the upper wing, is probably its analogue''.

8. Mesosternum". The central part of the 7?^^^Z^>ec^^^s,
or that which passes between the mid-legs when ele-
vated, protended, or otherwise remarkable, is called the
mesosternum or mid-breast-bone. In the Coleoptera Or-
der it exhibits the most numerous variations, and is
usually the most strongly marked of any of the three
portions of the sternum, affording often important cha-
racters for the discrimination of genera and subgenera.
It may be said to be formed upon three principal types—
the first is, where it is a process of the posterior part of
the peristethium, and points towards the anus or the
head ;— the second, where it is a process of the anterior
part of the mesostethium, and points only towards the
head: in this case there is no suture to separate the

=. Plate IX. Fig. 8. a. " Ibid. Fig. 12. o'.

Plate VIII. Fig. 3, 13./.

EXIUKNAL ANATOiMY OF INSECTS. 567

medipectus from the postpectus — the last type is where
it is a ridge formed by a process both of the peristethium
and mesostethium meeting between the legs ; an example
of this you will see in the common dung-chafer [Geo-
tnipes Latr.). Upon the two first of these cases I shall
offer a few remarks ; — the last affording no variation
need only be mentioned.

If you examine the terrestrial Predaceous beetles
{Cicmdela and Carabus L.) you will find that the periste-
thium is usually flat, terminating towards the postpectus
in a kind of fork, the sinus of which receives the anterior
point of the mesostethium — this is the mesosternum ; but
in the aquatic insects of this tribe, at least in Dytiscus
marginaliSi &c. the structure at first sight seems diffe-
rent, for apparently the prosternum is received by the
anterior fork of the mesostethium ; but if you proceed to
separate the manitrunk from the alitrunk, you will find
that the true mesosternum of the usual form is quite
covered by this point, which curves towards the breast,
is longitudinally concave to receive the point of the pro-
sternum, and permit its motion in the groove. In some
Heteromerous beetles, as the Helopidce, &c. this part is
anteriorly bilobed, so as to form a cavity which receives
the point of the pi'osternum when the head is bent down :
in Helops nitens {Tenebrio Oliv.) this sinus represents a
crescent; in Cistela Ceramboides ii is shaped like the
Greek letter y; in the Lady-bird {Coccinella L.) it as-
sumes nearly the shape of a Saint Andrew's cross ; in
Spheniscus K.* the mesosternum is wide, concave and
wrinkled, with an anterior and posterior sinus ; while in

* Linn. Trans, xii. t. xxii./. 4.

568

EXTERNAL ANATOMY OF INSECTS.

the analogous genus Erotylus^ it is convex anteriorly,
and posteriorly more or less rounded ; in Doryphora it
is a long, robust, subconical horn, often standing at an
angle of about 45°, overhanging the prosternum.

In the genus last named, though its mesosternum in its
direction and appearance resembles that of many Peta-
locerous beetles, yet it is separated by an evident suture
from the mesostethmm ; but in the last-mentioned tribe
its representative is a process of the latter part : yet as
the peristethium and mesostethium are separated by no
suture, though in some cases a transverse channel, and
in others merely a coloured line, marks the point where
they may be considered as soldered together, in these
cases the mesosternum may perhaps be said to be
common to both. In this great family, which includes
within its limits some of the most singular and wonder-
ful in their structure and armour, as well as some of the
most brilliant and beautiful of the beetle tribes, — the part
in question, in a vast number of cases, will enable the
Entomologist satisfactorily to trace its numerous groups,
not only where it rises or stretches out into a horn or
ridge, but even often where it is merely a flat space be-
tween the mid-legs. I shall notice some of its most
striking variations in this tribe. In Phanceus festims,
and in Macraspis and Chasmodia MacLeay, it is elon-
gated horizontally, with the apex curving upwards ; in

a A remarkable instance of analogy is afforded by this genus. In
Erolylus there are two groups ; one distinguished by gibbous elytra,
and the other by flatter ones. The same distinction is obser^^able in
Spheniscus ; for to this genus belongs Helojjs fascintus Oliv., which re-
presents the flat Erotylt, and even individually Eroiylus trifasciatus
Oliv., E.fasciutus F.

EXTERNAL ANATOMY OF INSECTS.

569

Anoplognathus it is horizontal, straight, and figures an
isosceles ti-iangje; in Cetonia suturalis, mtticollis, &c.
it is very long, passing between the arms and nearly
reaching the head ; in C. marmorea, Lanius, &c. it is a
lofty, robust, conical prominence; and in many Rute-
lid(E, especially those with striated elytra, it is pyramidal
or four-sided ; it varies also in its termination, particu-
larly in the Cetoniadce ; and even where there is little or
no elevation of it, as in the Scarabceidce MacLeay, it is
often terminated anteriorly by lines that vary \n their
angle or curvature. The genus Copris, as restricted by
Mr. W. S. MacLeay, may from an inspection of this
circumstance be divided into several families. Thus in
C. Molossus and affinities its termination represents the
letter ^ reversed, or a triangle surmounted by a mucro ;
m C. orientalis, &c., it ends in an acute-angled trian-
gle ; in C. lunaris, &c. in an obtuse-angled one ; and in
C.Iacchus, &c., in the segment of a circle.

The part we are considering is not so important in
the other Orders. In the Orthoptera, however, it is occa-
sionally remarkable. In Acrida viridissima ( Loaista F.)
attached to the anterior margin of the pe^-istethium are
two long triangular pieces which appear to represent this
part; in the kindred subgenus, ConocepJialus \ it is a
single piece bifid at the apex ; in Gi-yllotalpa it is a very
elevated hairy ridge; and in Locmta Leach, it is a flat
anterior process of the mesostethium. In the Heteropte-
rous Hemiptera this part is often merely a portion of
the channel in which the prormiscis reposes; but some-
times, as in Edessa R, it is an elevated piece varying

* I would restrict this name to the conical-headed Locmt<c F.

570 EXTERNAL ANATOMY OF INSECTS.

in its termination. In the remaining Orders, as far as I
have had an opportunity to examine them, it can
scarcely be said to exist separately from the medipectus,
except that in Tipula Latr. a bipartite subtriangular
membranous piece seems to be its analogue.

We are now to consider the last segment of the ali-
trunk, which, as a whole, may be denominated the po-
truncus; it bears the second pair of the organs of flight,
and the last pair of legs. The upper side of this is the
metathorax, and its lower side the j^ostpectus.

9. Postdorsolim \ The fii^st external piece of the
metathorax is the postdorsolim, which presents itself
under very different forms and circumstances in the dif-
ferent Orders. In the Coleoptera it is intirely covered
by the dorsolum and scutellum ; it is generally more or less
of a membranous substance, or partly membranous and
partly corneous, which enables it to yield more to the
action of the wings in flight; it is usually an ample
transverse piece with tumid sides ^ ; but in the Scarahmdce
MacLeay, it is short though very wide; and in Cyclmis,,
and probably other apterous beetles, it is extremely mi-
nute and almost obsolete. In the Ortlioptera Order, I
observe once for all, the part in question, as well as
the postscutellum and postfrcEnmn are mere counterparts
of the dorsolum, scutellum, and frMi, except that in
some cases they are larger c. In the Heteropterous He-
miptera at first sight it would appear that all the parts of
the metathorax were altogether wanting or absorbed

a Plate VIII. IX. i. Linn. Tram. xi. t. ix./. 16. c.

I' Plate VIII. Fig. 3. i'.

- Ibid. Fig. 12. Comp. «',^',''> with

EXTERNAL ANATOMY OF INSECTS. 571

in the ample scutellum ; but if you remove this with care,
you will find under it their representatives, its lower sur-
face being hollowed out to receive them. The postdor-
solum appears in these as a transverse obtusangular band ;
in the NejudcepSfotonedidce, &c. the three parts of the
metathorax seem united into a single plate, emerging
laterally from imder the smtellum below the frcenuni; in
which, however, some traces of a distmction between
them may be discovered. In the Horaopterous section
the Fulgoridcc exhibit these pieces very distinctly, cover-
ed only at the base by the mesotliorax : but in Tettigonia
they are not so easily detected ; they exist however as a
narrow strip or band, almost concealed by that part.
As to the Lepidoptera Order, in Pieris Brassicce at least,
the postdorsolum is represented by a pair of nearly equi--
lateral triangles whose vertexes meet in the centre of the
metathorax, and between which and the scutellum is a
deep cavity; but in Macroglossim Stellatarum and La-
siocampa Quercus, there appears to be also a central
transverse piece between them. In the Neuroptera there
is no material or strikmg difference between the parts of
the mesothorax and metathorax \ In the Ht/mmojJtera
more variety occurs in this part. In the saw-flies, &c.
{Tenthredo L.) the j^ostdor solum is a transverse piece
covered by the scutellum; in the Ichneumonidce it is
smaller, but not covered; in the Vespida it is apparent,
transverse, and with the postscutellum obtusangular t> ; in
Apis it is overhung by the scutelhm. The Diptera exhibit
some variations in this part. In Tipula it consists of
three pieces placed transversely, the central one qua-

Plati: IX. Fig. 7.

" Ibid. Fig 11.^'.

572 EXTERNAL ANATOMY OF INSECTS.

drangular, and the lateral ones roundish ; in the Asilidce
and most others of this Order, with the postscutellum, it
forms a segment of a circle % sometimes armed with a
pair of spines, as in Stratyomis R, and is what has been
usually regarded' as the real scutellum, though, as I have
endeavoured to show, not correctly''.

10. Postscutellum^. The postscutellum hears the same
relation to the postdorsohm that the scutellum does to the
dorsolmi, but it is seldom, if ever, a distinct piece. In the
Coleoptera it is represented by the longitudinal narrow
channel that terminates the postdorsolum towards the
anus"* : this usually figures an isosceles triangle with the
vertex truncated or open; but ii Copris the triangle is
equilateral. In the other Orders it is little more than
the central posterior point of the postdorsolum ^

11. Postjrconum ^. The part now mentioned is much
more important than the preceding one, and must not be
passed over so cursorily. In the Coleoptera it usually
presents itself under the form of two large and usually
rather square pannels, the disk of which is convex, but
the rest of their surface unequal, which are situated one
on each side of the postscutellum s ; under the anterior
outer angle of these is the socket or principal attachment
of the secondary wings, and their basal margin is at-
tached to their outer side ; posteriorly behind the vertex
of the postscutellum the postfrcenum is crowned with a
ridge or bead, below which it descends vertically or
obliquely to the adomen ; this ridge often turns upwards,

H Plate IX. Fig. 19, 20. t' . ' See above p. 558-.

c Plates VIII. IX. u. *' P^-^^^^ VIII. Fig. 3 « .

« Ibid. VIII. Fig. 12. u. Plate IX. 7- ,
'Plate, VIII. IX. « Plate VIII. I'lo. 3. . .

EXTERNAL ANATOMY OF INSECTS.

573

and proceeds towards the middle of the basal margin of
the wing. In the Petalocerous beetles the part in ques-
tion is usually more or less hairy ; but in many others,
as the rose-scented Capricorn [Callichroma moschatum),
&c. it is naked. At its side you will commonly observe
several plates and tendons {osselets Chabr.) connected
inter se and with tlie base of the wing by elastic liga-
ments, which are calculated to facilitate the play of those
organs. In the Orthoptera, Neicroptei-a, and Homopte-
rous Hemiptera, the postfraenum does not differ mate-
rially from the/rcenum In the Heteropterous section
of the last Order it is usually a transverse ridge termi-
nating the postdorsolum, with a bifurcation where it
imites with the wing; but in Teti/ra F. (at least so it is
in Tetyra signata,) it is a nearly vertical piece, marked in
the centre with an infinity of very minute folds, which
probably by their alternate tension and relaxation let
out and pull in the wings. Amongst the Lepidoptera it
is not remarkable. In the Hymenoptera Order it is
mostly represented, I thmk, by a double ridge or fork,
sometimes however obsolete, but very conspicuous in the
saw-flies, which laterally terminates the postdorsolum;
the upper branch, usually the thickest, going to the an-
terior part of the base of the underwing, and the lower
one to the posterior. You may observe something simi-
lar in the crane-flies {Tipula Latr.) and Asilida. A
tendon proceeding from the point of the postscutellum
forms a fork near its end, the upper branch of which
connects with the anterior and the lower with the poste-
rior valve of the winglet; the structure is a little, but not
essentially, different in other Diptera.

" Pr.ATE Vin. Pig. 12. 16.; and Plate IX. Fig. 7. v'.

574? EXTERNAL ANATOMY OF INSECTS.

12. Pleura ^. By this name I would distinguish the
part which laterally connects the metathorax and 'po&t-
pectus. It includes in it the socket of the secondary
wmgs. In the Coleoptera this is a two-sided piece lying
between the postfranum and the parapleura, with the
upper side horizontal and the lower vertical ^ — a tendon
usually proceeds from its anterior extremity to the base of
the wmg. In the Orthoptera, Neuroptera, and other Orders,
it is merely the longitudinal Hue of attachment of that
part ; but in the genus Belostoma Latreille, related to the
water-scorpion, it presents a peculiar structure, being a
deep channel or demitube, filled at its posterior extremi-
ty by a spiracle and its appendages <=.

13. Metapnystega ^. This part, although in the table I
have placed it as an appendage of the pleurcE, is not always
confined to them, as you will soon see. It either covers
aerial vesicles, or is the seat of a spiracle. In the Order
Coleoptera it is of the former description. If you exa-
mine the metathorax of the common dung-chafer {Geo-
trupes stercorarius), in the horizontal part of the pleura
you will see a sublanceolate or subelliptical rather mem-
branous silky tense plate, with its pomt towards the head,
—this is the part we are considering; sometlimg similar
you will find m most beetles; but in some, as CaUichro7na
moschatum, it is less conspicuous. This part, as far as I
have observed, is not so situated in any other Order, ex-
cept in some Heteropterous Hemiptera: in Belostoma the
channel lately mentioned is filled up at its posterior end
by a red organ with an anterior vertical fissure, tenni-

^ Plate VIII. Fig. 3. t:-'. " Plate XXII. Fig. U. w.

Plate XXIX. Fig. 25. lu .
" Ibid, and Plate VIII. Fig. 12. ; and Plate IX. Fig. 7. k .

EXTERNAL ANATOMY OF INSECTS, 575

nating behind in a conical bag : in Notonecta the pleura
has something of a plate hke that of Coleoptera, but of
a horny substance. In the Orthoptera and Neuroptera
this part changes its situation, if it be indeed synony-
mous ; and as the pnystega follows the frcenum, so the
metapnystega succeeds the postfrcenum. In the Libellulina
M. Chabrier found that this as well as the other covered
aerial vesicles and it probably does the same in the
other cases in which it occurs. In Mantis and Phasma
in the Orthoptera it is very minute; but in Locusta
Leach, it is more conspicuous under the form of a tense
membrane, the surface of which is depressed below that
of the abdomen : in Acrida viridisshna K. it fiUs the
sinus of the postfr-atium, and is vertical, as it is in
JEshna. It is worthy of remark that this piece bears
some analogy to that below the ridge of the pai't just
named in Coleoptera, which descends either vertical-
ly or obliquely to the abdomen''. A similar space,
though often nearly obsolete, may be seen in the Hemi-
ptera and Lepidoptera. But the Orders in which this
part is most conspicuous are the Hymenoptera and Dipte-
ra^ and in these its aerial vessels are connected with a
spiracle. In Tenthredo L. and Sirex L., what Lmne
named grana, from their situation, should be regarded as
belonging to the pnystega^ and whether there is any part
representmg the metapnystega I am not quite satisfied ;
perhaps the membrane at the base of the abdomen in
Tenthredo, and the bipartite piece, apparently its first
segment, in Sirex may be its analogues : but in the great
majority of the Order, the convex or flat piece that in-

» Surle Vol des Ins. c. iii. 354. See above, p. 572.

• Plate IX. Fig. 15. k" .

576

EXTERNAL ANATOMY OF INSECTS.

tervenes between the j)ostdorsolum and its adjuncts and
the abdomen, and which bears a spiracle on each side,
is the metapnystega This part is often remarkable,
not only for its size, but for the elevated ridges that
traverse it, as in Ichneumon, Chlorion, &c. In the last
genus it is of a pyramidal shape, with the anterior part
horizontal and the posterior vertical; it is altogether
vertical in Vespa, Apis, &c. Amongst the Diptera, in Ti-
pula it is nearly horizontal, and shaped like a cushion ;
but in general in this Order it is vertical, and concealed
under the postdorsolwn^.

We are now to consider the parts that constitute the
postpectus or under-side of the metathorax, and which
bears the posterior pair of legs.

14. Mesostethium". This part in Coleoptera is termi-
nated anteriorly by the peristethium, scapulais, and me-
sosternum, laterally by the parapleurce and behind by
the coxcs of the posterior legs % which generally are in-
serted transversely between it and the abdomen. It is
commonly very wide ; but in Dytiscus L., Carabus L.,
&c., in which the coxes and parapleurce are dilated, it is
proportionally reduced : its length is regulated by the
distance of the intermediate and posterior legs ; where
these are far asunder, as in the rose-scented Capricorn
{Callichroma moschatum), &c. it is long : but where they
are near each other, as in the Scarabceidce MacLeay, it
is short; its width, however, generally exceeds its length.
In shape it is generally subquadrangular though some-

" Plate IX. Fig. 11. k" . " Ibid. Fig. 20. A".

« Plates VIII. IX. y. " Pi-ate VIII Fig. 4. z.

. Ibid. ;/'. ' Ibid.y.

EXTERNAL ANATOMY OF INSECTS. 577

times rhomboidal, and other forms of it occur. Between
the hind-legs it generally terminates in a notch or bifur-
cation distinct from the melasternum, as in Hydrojyhilus,
&c. ; in Hisler there is no notch, and in many Scara-
Imidce it projects between the hind-legs in a truncated
or rounded mucro; in the Vesicatory beetles, Meloe
I.., it is more elevated than the medipectus, towards
which it descends almost vertically; in Dijtiscus L., Ca-
rahus L., &c,, this part is usually divided into two by a
transverse sinuous channel, and in Elaler by a longitu-
dknal straight one. In many Orthopterous genera, Gnjl-
lotalpa, Acrida K., Locusla Leach, &c., the mesoslelhium
consists of two pieces It is remarka})le that in many of
these genera, in this part, as likewise in the medipectus and
anle.peclus^ are one or more perforations which appear to
enter the chest, the use of which I shall explain hereafter.
In the Libellulina, as I shall soon have occasion to shew,
there is a peculiar arrangement of the legs and wings, in
consequence of which this partis placed behind the pos-
terior ones. In the remaining Orders, the mesostethium,
though it exists, exhibits no peculiarities worthy of par-
ticular notice, except in some Aptera and Arachnida :
thus, in Nirmus Anseris it is terminated posteriorly by
a pair of transverse membranous appendages which
cover the base of the posterior coxce in Scorpio it con-
sists of two pieces, the pectines^ bemg attached to the
sides of the posterior one.

15. Parapleural. The parapleural speaking gene-
rally, is that piece of the postpectus which, intervening
between the pleura, mesostethium, and scapulars, is at-

- Plate VIII. Fig. 13. y. d f. " Plate XXVII. Fjg. 50.

' Plates VIII. IX. z-.

VOL. nr. 2 !•

578 EXTERNAL ANATOMY OF INSECTS.

taclied by its posterior extremity to the cox(S of the hind-
legs ; by means of the fleura, from which it does not
appear to be separated by any suture, it connects the
secondary or under-wings with the hind-legs, as the sca-
pular does the primary ones with the mid-legs ; so that
the direction of the jparajpleura depends upon the rela-
tive situation of the legs and wings. In Coleopterous
insects its direction is horizontal, it being generally a nar-
row subquadrangular piece that runs straight from the
posterior coxse to the scapular % and usually divided into
two unequal portions by an elevated or impressed line.
In the palm-weevil {Calandra Palmarum) this part is
wider than usual ; in Dytisais marginalis—\n which ge-
nus, as likewise in Carabus L., the coxa are incapable of
separate motion,— it is nearly a right-angled triangle,
and is divided longitudinally into two unequal portions.
In the Orthoptera Order this part usually consists of two
equal portions, and its direction is sometimes nearly hori-
zontal, as in Mafitis and Phas^na, sometimes forming an
angle with the horizon, as m Blatta ; and sometimes
nearly vertical, as in XocMste Leach. In the two first cases
the wings are before the legs, and in the last their po-
sition is over them. In the Heteropterous Hemiptera
it is paraUel with the scapular, is divided into two un-
equal portions, and its direction is more or less inclmed
to the horizon ^ As to the Homopterous section— m Ful-
gora it is of a very irregular shape with an angular surface,
and its direction from the leg to the wmg is first nearly
vertical and then horizontal: in Tettigonia it is almost
vertical, and consists of two nearly equal portions. To

» Platk VIII. Frc. 4. " XXIX. Fro. 15.

EXTERNAL ANATOMY OF INSECTS.

579

come to the Neuroptera — in the Libellulina it consists of
two pieces, like those of the scapulars, but smaller and
its inclination is towards the head : in Panorpa also it
resembles the scapulars both in form and other circum-
stances ^ In the remaining Orders it exhibits no very
remarkable features.

16. Metasternum^. The central part of the w^sosif^-
thium when elevated or porrected, or otherwise remark-
able, is called the metasternum. In the Coleoptera, in
those cases, as we have seen above in which the me-
dipectus and postpectus form one piece, its anterior point
becomes the mesosternum but in others, as the Preda-
ceous and Capricorn-beedes, &c., it is received in a sinus
or fork of that part, or meets it. It is usually neither
so remarkable nor important as the mesosternum. In
Bolbocerus K. it is a rhomboidal elevation : in Gyrinus a
ridge; as also in many Hydrophili, in which it passes
between the hind-legs to the abdomen, and terminates in
a sharp point''; and in Dytiscus its two diverging lobes
cover the base of the posterior trochanters In the
Orthoptera Order this part is not remarkable ; but in
Acrida viridissima K. it consists of three triangular pieces,
the lateral ones being erect, and the intermediate one ho-
rizontal: in Locusta Leach it resembles the mesosternum^.
In the Heteropterous Hemiptera the whole mesostethium
is elevated, and terminates at both ends in a fork, the
anterior one receiving the point of the promuscis, and the
posterior one that of the epigastrium : in the Homopte-
rous section, the Tettigonice F. have usually a distinct me-

Plate IX. Fig. 8. z". Plates VIII. IX. a f.

' See above, p. 565. J Plate VIII. Fig. 8. a f .

• De Geer iv. t. iv.f. s. dd. ee. f Plate VIII. Fig. 13. a f.

2 p 2

580 EXTERNAL ANATOMY OF INSECTS.

tasternal point between their hind-legs. In the remaining
Orders there is no metasternum, or no remarkable one,
except in one singular Hymenopterous genns.Evania, the
parasite of the BlattcB \ in which there is a forked pos-
terior process of the mesostethium with recurved points.

17. Opercular. By this term I distinguish those
plates, before largely described S which cover the drums
of male Tettigonice F. ; and likewise those called also by
the same name by M. Chabrier ^ which cover, in many
cases, the vocal apparatus of the trunk of insects : those
of Melolontha vulgaris he describes as situated below the
wings, and between the two segments of the alitnmh^ :
and if you take this insect and remove the elytra, the
mesothorax and scapulars, under the latter and below the
wing you will find an oval convex plate, which is pro-
bably the part he is speaking of ;— but it is better exem-
plified, I think, in the common Dytiscus marginalis, in
which it is very distinct as a convex subtriangular plate
connected with the metathoraxhy mernhx^nons ligament,
covering a kind of pouch, and appearing to open and
shut at the vertex "\

I must here observe, with regard to the Aptera and
Arachnida, that the trunk in them is much more simple
than in those msects that are furnished with r^ings. In
the hexapods, in the former Orders, though there are

" The history of this parasite has been traced by Dr. Reid; but
alas I this learned and acute observer of nature did not live to give
his discoveries to the world : it is hoped, however, they will not be
lost, being in most able hands.

^ Plate VIII. Fig. 18. and XXII. Fig. 13. c f.

e Vol. II. p. 405. " Sur le Vol des Ins. c. i. 459.

EXTERNAL ANATOMY OF INSECTS.

581

usually three pedigerous segments, there is no distinction
of dorsolum, scutellnm, &c. In the Scolopendridce and
Scutigera amongst the Myriapods, according to the acute
observations of M. Savigny ^, — on which, however, some
doubt at present rests, — there is a remarkable formation,
tlie whole thorax being represented by the single plate
that follows the head, to the under-side of which are at-
tached the first and second pair of palpi or pedipalpi,
and the first pair of legs, representing the three pairs of
legs of hexapods. In the Iididie the three segments that
follow the head, each bear a single pair of legs, while all
the rest bear a double one : from whence it should seem
to follow, that these segments and then* legs represent
the trunk and legs of Hexapods. In the Octopod Aptera
and the Arachnida the trunk consists of a single piece,
not separated from the head, and sometimes not distinct
from the abdomen.

V. Internal processes ^. Perhaps you will think that
this head would be better considered when I treat of the
Internal Anatomy of Insects; but as the parts included
under it are really processes of the external integument
of the trunk, it seemed to me best to treat of them under
that head. They are of two descriptions ; processes of
the thorax or upper part of the trunk, and processes of
the breast or its under part.

i. Processes of the thorax"^. These are the phragma,
prophragma, mesophragma, and metaphragma. The first
belongs to the prothorax, the second to the mesothorax,

" Mem. sur les Anim. sans Verlebr. 45 — . Hor. Entomolog. 411 — .
^ Plate VIII. Fig. 3. x' . IX. Fig. 2. s. and XXII. Fig. 5—
14. <= Plate XXII. Fig. 8— 11.

582 EXTEllNAL ANATOMY OF INSECTS.

and the two last to the metathorax ; each forming a kind of
chamber of the under-side of each segment of the thorax.

1. Phragma, The phragm, or septmn of the jJrotho-
rax, is most conspicuous in the mole-cricket {Gryllotal-
pa\ in which it is a hairy ligament attached to the inside
of the upper and lateral margins of the base of that part:
inclining inwards, it forms the cavity which receives
the mesothorax. It is not, however, without a representa-
tive in many Coleoptera, though in these it is less strikmg,
from its being smaller and taking a horizontal direction.
In Elater, by means of some prominent points received
by corresponding cavities of the vertical part of the base
of the elytrum, it forms a kind of ginglymous articula-
tion, which probably keeps them from dislocation in re-
pose, and, by the sudden disengagement of these points
from the cavities, assists the animal in jumping ^

2. PropJiragma ^ This is a piece usually ahnost ver-
tical, but in Elater horizontal; of a substance between
membrane and cartilage, descending anteriorly from the
dorsolum, and forming the first partition of the chest of
the mesothorax; it is generaUy much shorter dian the
mesophragm. Though very visible in Coleoptera and
the Heteropterous Hemiptera, in the other Orders it is
less easily detected, and is sometimes obsolete. It may
be observed here, that in the Hymenoptera, at least m
the wasp, the hive-bee, the humble-bee, and the Dipte-
ra mostly, the interior of the upper-side of the alitrunk,
instead oitwo, seems at first to be divided mto four cham-
bers, formed by sept^da : but as these ridges merely mark
out the internal limits of the dorsolum, scutellum, postdor-

n Vol, II. p. 318. " Plate XXII. Fig. 8, 11. A'.

EXTERNAL AN'ATOMY OF INSECTS.

583

solum, and metapnystega, the last but one of these being
usually less distinct, they seem not analogous to the three
pai-titions of the alitrunk in othei' Orders; so that in
these the mesophragm at least seems to have no repre- '
sentative, and the prophragm and metaphragm include
between them only one ample chamber. In the DijHera,
wherever there is an external dep-ession or suture there
is a corresponding internal ridge or seam, so that the
parts seem more distinctly marked out on the inside
than on the outside of the crust.

3. Mesophragma ^ This piece also, which forms the
middle partition of the upper part of the cavity of the
alitrunk, dividing it into two chambers, is most conspi-
cuous in Coleoptera. It is usually in them a vertical
piece, resembling the prophragm in substance, but twice
its height, of a quadrangular shape with a notch in the
middle ; it fills the sinus of the postdorsolum, the sides of
which sometimes descend below it ^. In this Order the
chamber that it forms with the prophragm is very small <=,
the motions of the elytra requiring no powerful apparatus
of muscles; but that which it foiTOs with the metaphragm,
which is appropriated to the muscles moving the wings,
is very large In die Orthoptera the anterior chamber
is larger than in the preceding Ordei-, which proves that
tegmina are more moved in flight than elytra. In the
Heteropterous Hemiptera a remarkable variation takes
place— the anterior being larger than the posterior
chamber; which last, in fact, consists of two, one for each
wing : in these the mesophragm towards the abdomen
forms an angle, which in Pentatoma, &c., is acute; in

» Plate XXII. Fig. 9, 1], ,'. b ^lo. 9. a a.

*" Ibid. F'iG. 11 . a. a

584 EXTEENAL ANATOMY OF INSECTS.

Belostoma a right angle, and in Notonecta an obtuse
one. In the two first the angle of the mesophragm sends
two short diverging ridges to the metaphragm ; and in
the last only a single one: in this also the posterior
chambers together are nearly as large as the anterior.
From this structure it should seem that in flight the
Hemelytra are more important than the wings. In the
Homopterous section the anterior chamber is the
smallest, at least in Fulgura candelaria; and the meso-
phragm is lofty and bipartite. In the Lepidoptera the
anterior chamber is the largest, and the part in question
conspicuous In the Libellulina and Hymeiioptera it
is merely represented by a low ridge, and in the Diptera
it seems evanescent.

4. Metuphragma ^. This, in many cases, is the 'largest
and most remarkable of the three partitions of the upper
portion of the cavity of the alitrunk, which separates it
from that of the abdomen ; it is attached to the posterior
margin of the metathorax, and is nearly vertical : in sub-
stance it may be stated as rather firmer than the two
preceding partitions. In the Coleoptera it is commonly
of the width of the posterior orifice of the alitrunk ; and
its centre is cleft so as to form a deep sinus ^ for the
transmission of the intestines,— a circumstance which
also, though less conspicuously, distinguishes the meso-
phragm '^r from this sinus it slopes gradually towards the
sides, and is sometimes armed with an intermediate pro-
cess on each side <=. This structure you will find exem-

» Plate IX. Fig. 2. s'. , . ^ ■ , w-

"Plate XXII. Fig. 10, 11. ComP" f/^^^ ^''"^ n ,
^ „ c Plate XXII. Fig. 10, 11. a.

■ ' •> ibid. Fig. 9. c. ' Ibid. Fig. 10. a.

EXTERNAL ANATOMY OF INSECTS. 585

plified in the common cock-chafer and many others of
the Order. I have not, however, discovei'ed traces of
it either in the Silphidce, Staphylinidce, or the vesicatory
beetles {Meloe L.) ; or even in such species of Carabiis
L. and Cicindela L. that I have examined; vsrhile in
Dytisms it is very visible. In the Orthoptera it is nearly
obsolete ; but in Locusta Leach, under the metapnystega,
one on each side, is a pair of seemingly pneumatic
pouches which may be mistaken for it. It is almost
equally , inconspicuous in both sections of the Hemiptera.
As to the Lepidoptera, — in Pierh Bmssicce, it resembles
in some degree, though in miniature, the metaphragm of
the Coleoptera ; but in Sphinx Stellatanm and Lasio-
campa Quercus it has a sinus on each side, but no middle
one. In Panorpa it nearly closes the posterior orifice
of the trunk, but in the Libellulina it is a mere ridge.
In some Jrlymenopteva^ as Cimhex sericea^ the drone-bee at
least, &c., it is a large convex bifid piece. In the wasps,
under the spiracle of the metapnystega on each side,
as in the Locusta^ is what I also take to be a pneumatic
pouch, which might easily be mistaken for a metaphragm.
In the Diptera Order this part is very conspicuous. If
you remove the abdomen of any common Tipida, you
will find that the posterior orifice of the trunk is closed
above by a pair of oblong, vertical, convex, divei-ging
plates ;— do the same by any fly {Musca L.), and you will
detect in the same situation a very large convex or gib-
bous one notched below, which occupies almost the whole
orifice : this is the metaphragm.

5. Septtda These are the smaller ridges of the inte-
rior of the alitrunk, which afford a point of attachment to
» Ibid. Fig. 0—11./".

586 EXTERNAL ANATOMY OF INSECTS.

many muscles, and run in various directions both on the
interior of the crust and of the metaphragm. These Utde
seams are not to be found so generally in the other Or-
ders ; but very frequently, as has been before observed,
where there is an exterior impression of the crust, or a
suture, one of these forms its internal base.

ii. Processes of the pectus^. We are next to consider
the internal processes of the breast of insects: these con-
sist for the most part of the cndosternum, or internal
sternum, and its branches. As the principal feature of
this are the processes which rising from it serve as points
of attachment to the muscles that move the legs, &c., I
shall confine myself to them— they are, the antefurca, the
medifurca, and the postfurca.

1. Antefurca^. The first portion of the endosternum,
or the internal prostermcm, branches into the antefurca.
In the Coleoptera a plate varying in shape and direction
sends forth a pair of mostly vertical processes of a car-
tilaginous substance ^ differing in height in different
genera. In Carahus L. there is neither this plate nor its
processes ; but in Dytiscus the latter are very visible. A
very singular and complex machine represents the part
we are considering in that extraordinary insect the mole-
cricket {Grt/llotalpaLatr.). When we look at its prodigi-
ous arms and consider their office % we may imagine that
the requisite apparatus for moving them must be very
powerful and peculiar. Their Creator has according-
ly provided them with a machine for this purpose more
than usually complex, extending from the prothorax to the

a XXII. IMO. .5-7. ^ Ibid. Fig. 7. J Ibid- a.

" Ibid. e. ^ See above, Vol I. p. 191. and II. p. 257, 366.

EXTERNAL ANATOMY OF INSECTS.

587

prosternum; tlie former being its base^ and the latter its
vertex. The cavity of the manitrunk is divided longi-
tudmally by a double cartilaginous partition surmounted
by a bony frame, with an anterior condyle or tuberosity,
with which the inner part of the base of the clavicle of the
arm appears to ginglymate ; and the manitrunk is pre-
served from the injury the powerful action of the arm
might occasion, by the counteraction of this machine, to
describe which fully, would demand more space than I
can afford ^ I mentioned under theinesostethium, the aper-
tures visible in the breast of Loctista Leach and Acrida K.
Each of these apertures opens into an internal, tubular,
horny, process, which arching off is attached at the
other extremity to the sides of the trunk— a pair being
appropriated to each segment; the first analogous to
the antefurca, the second to the medifurca, and the last
to the postfurca. In the medipecttis and postpectus of
Acrida viridissima there is only a single aperture, termi-
nating in a single tube, which after rising vertically a
little way sends off a branch on either hand to the sides
of the trui^k. Where there are three of these holes, as
in the antepectus and medipectus of Locusta Dux, there
are three of these processes, the intermediate one being
vertical. In the subsecjuent Orders the processes of the
endosternum are not sufficiently remarkable to require
particular notice: my fiirther observations upon them
will therefore be confined to the Coleoptera Order.

2. Medifurca ^ This part, which belongs to the mid-
legs, IS mmany cases more conspicuous than the antcfurca.

• This machine is described by Dr. Eschscholtz, BciiraRe zur

Nalurhmde, &c. Heft. i. 24 , t. i. ii,

" Plate XXII. Fig. 6. ' '

588 EXTERNAL ANATOMY OF INSECTS.

In Copris Molossiis the endosternum of the mcdipectus is
represented by a transverse zigzag ridge ^ between the
sockets of the mid-coxee, from which proceeds a pair of
branches wide at the base and growing gradually more
slender to the extremity'', which is attached to the sides
of the trunk; in Dytiscus marginalis a pa\r of slender, ver-
tical, straight processes, fitted with a broad cartilaginous
plate at their apex, rises from the endosternum, and sends
forth a lateral one to the side of the medipectus : and lastly,
in Carabus the medifurca is represented by a pair of sub-
triangular lamincE attached to the sides of the trunk.

3. Postfurca This, which belongs to the hind-
legs, is the most remarkable of the pectoral processes,
and has been noticed by more than one writer It is
a kind of trident, the branches ^ of which are acute, and
on their upper surface longitudinally concave, elevated
on a footstalk ^ inclined towards the viedifurca, consist-
ing of two plates, a posterior one supporting the lateral
branches, and an anterior or interior one forming a right
angle with the other, supporting the intermediate one.
This footstalk rises from between the posterior coxa,
which appear in the Lamellicorns to ginglymate with it at
its base. The middle branch of the trident dips to the
sinus of the medifurca. In Dytiscus viarginalis the form
is different ; for the intermediate branch consists of two
parallel pieces, and the lateral ones are dilated into broad
vertical plates: the stalk of this is triquetrous, and a tri-
ple cartilaginous partition appears to go from its base
anteriorly, the lateral ones diverging to the sides of the

^ Plate XXTI. F.g. G. a. " Ibid. b. ' Ibid. Fig. 5. b \
■I MacLcav, H.nc Enlov.olog. 9. Cliabrier, Sur le Vol deslm.
i 417 ■ Plate XXII. Fig. 5. bbb. ^ Ibid. c.

EXTERNAL ANATOMY OF INSECTS. 589

trunk, and the intermediate one running straight to the
base of the medifurca.

It may not be without interest to state here some of
the several objects and uses of this structure of the
trunk. When our Saviour says to his disciples, « But
even the very hairs of your head are all numbered" ^—
he taught them that the attention and care of the Deity
were not confined to the mighty and the vast, but
directed to every atom of his creation— that he not only
decreed the number and magnitude of the planets and
planetary systems, and of then- various inhabitants, but
that the most minute and apparently insignificant part
of each individual, both as to its number and form, was
according to the law by him laid down; and whoever
studies them with attention will find that insects furnish a
very interesting homily upon this text; since in various
instances I think I have made it clear, that parts seem-
mgly of the least importance— as a hair, a pore, or a
slight impression— have their appropriate use ^ At first,
it would seem that the various pieces of which we have
seen the second primary segment of the trunk of these
animals to be composed, would be of Httle importance;
but when we reflect that this multiplicity of parts is
usually not to be found in those that have no wings,
whether they be apterous sexes or tribes % a suspicion
arises in the mind that they must be of morfe consequence
than \h^xx prima facie appearance seems to warrant:— and
this IS really the case. The manUrunh, which is destined
pnncipaUy to incase the muscles that move the arms,
did not require to be so complex as the part that had to
support the action of mngs as well as legs. In those that
^ Luke xii. 7. ^ See above, p. 3.07-. ^ See above, p. 580.

590 EXTERNAL ANATOMY OF INSECTS.

have a large prothorax, as the Coleoptera, it may, indeed,
be useful in flight as a counterpoise to the abdomen;
and since when the wings descend it rises, and vice versa,
it may be of some service by its vibrations ; but for this
it required no complexity of structure. But not so the
alitrunk : it consists of parts much more numerous, and
this number of parts is of great unportance to the animal
in its flight. All of them are so put together, being lined
by a common elastic ligament ^ as to be capable of a
certain degree of tension and relaxation, which enables
the animal to compress or dilate the trunk as its ne-
cessities require. To cause the elevation of the wings,
it must be compressed or have its longitudinal diameter
increased, and its vertical and transverse diminished:
this compression is produced by the condensation of
the mternal air, which parts with some of its caloric, and
by the action of the levator muscles. To cause the de-
pression of the wings, it must be dilated, or have its longi-
tudinal diameter diminished, and its vei^tical and trans-
>oerse increased, which is effected by the rarefaction of
the internal air, and the action of the depressor inusdes- .
In some Orders, the Coleoptera, &c., this effect is pro-
moted by the segments of the trunk, which are attached
by loose ligamentous membranes, and received, one or
more of them, into each other, which faciHtates die
above action \ Thus much for the general use of these
parts. I shall further here mention a partial one of
two of them which seems indicated by a particular cir-

Chabrier Surle Voldes Ins. c. i. 413—
*> See above
'• Chabrier
d Ibid. 412

>> See above, p. 402. ,.o a^^

Chabrier Sur le Vol des Ins. c. i. 446, 448, 451—

EXTEJRNAL ANATOMY OF INSECTS. 591

cumstance, and upon which a theory may be built. In
some insects the primary and secondary wings or their
analogues are placed before the legs, in others om- the
legs, and in others behind the legs : but whatever their
position, the pieces which I have named the scapzdaria
and parapleurcB invariably connect the one with the
other; the former, the primary wings with the mid-legs,
and the latter, the secondary wings with the hind^legs.
This circumstance seems to prove that the wings by the
intervention of these pieces have an action upon the legs,
and the legs upon the wings; and this is further proved
in one case by an observation of M. Chabrier with re-
gard to Melolontha w^/^«r/5,— that the levator muscles of
the wings, by means of a long tendon, are attached to
the lower part of the posterior cox^ ^ Now, more than
one medical friend has suggested to me, that what are
called the coxcb in insects are really analogous to the
thighs of vertebrate animals ^• consequently these parts
must represent the coxce ; whence it would seem that the
wings are reaUy appendages of the legs. It must, how-
ever, be observed, that were this opinion admitted, in the
Aptera, Hymenoptera, and Diptera, or even in the pro-
thorax of other insects, there would scarcely be any ana-
logue of the coxce at all distinct from the trunk itself, of
which even in the other Orders these pieces are com-
ponent parts. An instance occurs in the Strepsiptera K.,
and in which the arms are furnished with an alary ap-
pendage, and the metathorax has none <=.
Ubi supr. c. ii. 333.
" According to M. Chabrier, who agrees with him, M. Latreille
also IS of opinion, that the parapleura is the analogue of the poste-
rior coxe. Ubi supra, c. ii. 31 2. Note 2.

M. Latreille has changed the denomination of this Order to

592

EXTERNAL ANATOMY OF INSECTS.

VI. Organs of Motion. We are next to consider those
organs attached to the trunk of insects which are instru-
ments motion. These are principally those by which they
are transported through the air, and those by which they
move on the earth or in the 'water — their mngs and their
legs. I shall begin with the first, the nsoings These
are not formed precisely after any type at present dis-
covered in vertebrate anunals: in some respects they
have an analogy, to those of birds ^ ; in others, to the
dorsal fins of fishes : but, perhaps, altogether they ap-
proach the nearest to those of the dragon or flymg-lizard
{Draco volans L.), which do not, as in birds, replace the
fore-legs, are kept expanded by diverging bony rays,
and are connected with the hind-legs <=. As the Divine
Creator appears in his works to proceed gradually from
■ one type of structure to another, it has been supposed
by a learned physiologist of our own country, that in
winged insects, /oz^r of the legs of the Decapod Crustacea

Rhiphiptera, because at first he thought that these organs were
not at all analogous to elytra or wings ; but since, upon further
investigation, he appears to admit that they assist in flight {Aii-
nales Gener. des Scienc. Phys. VI. xviii. 8. Compare MacLeay, Hor.
Entom. 423. Note *), in common justice he is bound to restore
the name originally given to the Order. In the same place of
the work here quoted, M. Latreille also speaks of these pseud-
elytra, as I would call them, as appendages of the mesothorax : but
whoever consults Mr. Bauer's admii-able figures of Xcnos Pedal
{Linn. Tram. xi. t. ix.), and is awai-e of the unimpeached and
minute accuracy of that admirable microscopic artist, wUI be con-
vinced that they belong to the anterior legs, and consequently to
the prothora.v.

a Plate X. and Plate XXVIII. Fig. 18-23.

" Chabrier, Analyse, &c. 27-

<= N. Diet. d'Hist. Nat. ix. 508. V^'e have seen above (p. o/8.)
that the wings of insects are connected with their legs by the scapu/a
and 2>araplcura.

EXTERNAL ANATOMY OF INSECTS.

593

are represented by the four wings » : this opinion, how-
ever, is not yet fully proved ; a remark which may also be
applied to a more recent one of a celebrated French
writer, who seems to think their origin and structure
aez-ostatic, that they are auxiliary to the legs, and bor-
rowed in part from the respiratoiy organs ^. Were I
disposed to enter into these subtile speculations, I might
here recall your attention to the analogy that, in their
metamorphoses, exists between the Saurian Reptiles or
lizard tribe and insects, and conjecture that the wings of
the D7'aco are really representatives of the mid-legs of
Hexapods, thus preparing to disappear altogether ; but
I shall content myself widi throwing out this hint, which
you are welcome to pursue. The organs of flight in
general may be considered as to their number, kinds, and
compositio??.

i. Number. The most natural number is four, for this
obtains in the majority. In almost every Order, indeed,
there occur instances of insects that have solely a single
pair or none*^.

» MacLeay, Hor. Enlomolog. 413—. Mr, MacLeay's opinion seems
to receive some confirmation from a circumstance overlooked when
the larvcB of insects were treated of above (p. 130—), and to which
he alludes (41 1); namely, that in that state they consist of two seg-
ments more than in the imago; these follow the three pedigerous
segments, have no pro-legs, and are supposed to belong to the trunk
rather than to the abdomen. To make this circumstance bear upon
the question, it must be proved that in the perfect insect these seg-
ments in some manner become the back of the trunk and bear the
wings. This would not be more wonderful than many changes that
iare known to occur in insects.

Latrcille, Organization exterieiire des Ins. 173—.

"= For instance Meloe, the female glow-worm, Lygatus bi evipennis,
Ephemera diptera, Cynip.t aptera, neuter ants, &c. &c.

VOL. III. 2 <3

59if EXTERNAL ANATOMY OF INSECTS.

These, however, are only exceptions to the rule; but in
the Diptera, unless we consider the alulce^ the representa-
tives of the secondary wings as a distinct pair, there
are never more than two wings, and one instance is
known in which an insect of this Order has none^.
Certain genera or individuals of the Tetrapterous Orders
are also furnished with alulce: besides Ih/tiscus, Blatta,
Phalana hexaptera, which have been before noticed %
they may be detected in miniature in Ammophila K. and
affinities ; these all may be regarded in some slight de-
gree as insects with six wings.

ii. Kinds. Under this head we may consider the or-
gans of flight as to their situation and as to their sub-
stance. As to their situation, usually the first pair are
attached to the mesothorax, and the second to the meta-
thorax; but in one instance, as has been before ob-
served", in the Strepsiptera K., the anterior pair belong
to the manitmnk, and the posterior to the mesotJiorax.
As to their substance, they take the several denomma-
tions of elytra, iegmina, Jiemelytra, and wings, for the
most part according to its variations, as will be seen
more at large hereafter. Under this head I shall only
further observe, that in many instances the organs of
flight appear to be mere abortions or nidiments, which
serve to exemplify what has been more than once stated,
that the CREATOR has seen it good to approach to new
organs gradually as well as to new forms. Thus elytra are
mere rudiments that do not serve to protect the wings in
Atractocei-us ; tegmina in some species Phasjna, Acry-

» See above, p. 569. Chionea araneoides Dolni.

See above, p. 560, and Vol. II. 348, 352-.
See above, p. 591, Note c.

EXTERNAL ANATOMY OF INSECTS. 595

dhim, &c.; hemelytra in the bed-bug^; -joings in many
female moths, in Cryptus JmnijHerus a Hymenopterous
insect, &c.

iii. Composition. The structure of wings has been
before explained to you and I shall again have occa-
sion to allude to it; but here I wish to call your attention
to a circumstance that has not hitherto, that I recollect,
been adverted to; I mean that all kinds of organs of
flight, and it may be traced as we shall soon see even in
elytra, are divided longitudinally into three areas or folds;
the first or external one I call the Costal Area « from its
beginning with the costal nervure ; the second is the Li-
termediate Area'^] and the third is the Anal Area^.

Having made these observations with respect to the
organs of flight in general, I shall now proceed to consider
more at large the elytra, tegmina, hemelytra, and mngs.

1. Elytra. These are the wing-covers of the Coleoptera
Order, distinguished from tegmina by the absence of
nei-mtres, from hemelytra by the want of the membrane
at the apex, and from both by their unitmg in almost
every instance at the suture. I shall consider them as
to their substance; articidation with the tnmk; expan-
sion-, parts; shape; appendages^ sculpture; clothing;
colours, and uses.

1. Substayice. The firmness of the substance of elytra
IS usually regulated by that of the crust of the insect to
which they belong; in hard insects they are hard, and

De Geer, iii. t. xvii./. 10, 1 1.//. M. Savigny has noticed a part
m some Annelid£s, wliich lie regards as analogous to elytra. Systaiie
de, Annelides, 4, 9, 1 1. i> Vol. II. p. 346—.

Plates X. and XXVIII. b-. " Ibid, c: « Ibid, d:

2 o 2

596 EXTERNAL AN^ATOMY OF INSECTS.

in soft ones they also are soft. The most impenetrable
ones that occur to my recollection are those of Illiger's
o-enus Doryphora, and the softest and most flexile those
of Telephcynis, Meloe and affinities. With regard to in-
dividuals, they are mostly as hard as the prothorax, and
harder than the hack of the abdomen. Elytra also, as
far as my observation goes, are never diaphanous.

2. Articulation with the trunk. This is by means of
aprocessof the base oftheelytrum whichlcall the axis^
or pivot, attached by elastic ligaments, and certain litde
bony pieces {osselets Chabr.) in the socket under the side
of the anterior angle of the dorsolum \ You may easily
remove the elytra attached to the mesothorax from Geo-
trupes stercorarius, which will enable you to see the mode
of articulation with litde troubled

3. Expansion. It is by means of the bony pieces just
mentioned that the organs in question are opened and
shut^ under the action of the antagonist muscles. In
opening for flight the two elytra recede fi'om each other,
and are elevated so as not to retain their horizontal po-
sition, which would interfere probably with the play of
the wings, but form an angle with the body. When they
return to a state of rest, the sutures usually meet and
coincide longitudinally; but in some cases when closed,
as in Necydalis, &c., they diverge from each other at the
apex; and in Meloe, like the Orthoptera, to which that
o-enus approaches, one laps over the other.

4 Parts. The parts to be considered in an elytrum
are the areas, the axis, the suture, the margin, the epi-

a Plate XXVIII. Fig. 3-5. i'".

1' Chabrier Sur le Vol dcs Ins. c. i. 439.

c Plate XXVIII. Fi?.. 1 0. " Chabrier ubt supr.

EXTERNAL ANATOMY OI" INSECTS.

597

pleura, the base and apex, the a7igles, and the hypoderma.
At first it should seem as if an elytrum was not like other
wings divided into areas; but I think upon examuiation
it will be found that, though often nearly obsolete, these
are represented in it; for the epipleura^ with the recurved
part of the external margin seems to me analogous to the
Costal Area; the inflexed part adjoining the scutellum and
often going beyond it to the Anal, and the rest of the organ
to the Intermediate. All this you may see in the dung-cha-
fer, Geotmpes stercorarius. The axis ^ or pivot by which
the elytrum articulates with the trunk is generally placed
about the middle of its base, but nearer the scutellar
than the humeral angle, and varies in length and shape
in the different tribes, but not so as to merit particular
notice ; it may be regarded as composed of three parallel
pieces, one belonging to each area, that of the costal be-
mg the longest. In many these pieces are marked by no
hue of distinction, but in Macropus, &c., they may be readi-
ly traced <=. The suture is the internal margin of the
elytrum fi-om the point of the scutellum to the end. In
many beetles the right hand suture, looking from the
anus to the head, has a lower ledge or margin, and the
other, one more elevated, which when they are closed
hes upon the former ; in some Dynastidce there seems a
kind of ginglymous structure in this part, each suture
being fitted with a kind of ridge which is received by
a channel of the other; in these the suture is generally
marked out by an adjacent channel : but the most re-
markable structure of this part distinguishes the genuine
species of the genus Chlamys, in which both the sutures,

' Plate XXVIII. Fig. 6—8. d'". ^ Ibid. Fig. 3—5. 5"'
' Plate XXVIII. Fig. 3. - Plate X^Fig. 1. c'".

598 EXTEllNAI- ANATOMY OF INSECTS.

except at their base, are armed with little teeth, alter-
nating with each other like the cogs of a mill-wheel. In
apterous beetles the elytra are often connate, or have
both sutures as it were soldered together. The margin
or external edge of the elytra is generally formed by a bead
or ridge, which, except in the case of the truncated ones,
in which it is straight, curves more or less from the base to
the apex; this ridge is often recurved so as to form a kind
of channel between it and the disk of the elytrum, as may
be seen in the Dynastida; ; in some there are two parallel
ridges, as in Copris; in Siljjha the margin is dilated; in
HelMis and Cossyplius it is remarkably so and recurved,
so that, in conjunction with those of the jprothorax v^hich.
are similarly circumstanced, they give the animal some re-
semblance to a smallmodel of abarge. Though the raargm
of elytra is most commonly intire, yet in some beedes, as
Gymnopleurus lUig., a sinus is taken out of it; in Cetoma
it often projects at the base, and in Cryptocephalus m the
middle, into a lobe; in Phoherns MacLeay it is denticu-
lated, and in many Buprcstes more or less serrulated;
sometimes it terminates before it reaches the a^ex of the
elytrum in a tooth, as in many Carahi Latr. The epi-
pleura^ or side-cover is that part of the organ in ques-
tion, below the margin, with which it usually forms an
ano-le, being more or less inflexed, that covers the sides
of the body. It varies in different tribes, being some-
times obsolete, as in the weevils [Curculio L.); m the
Capricorn beetles it is very narrow; in Carahm, &c.,
dilated at the base ; in many Heteromerous beetles, as
Blaps, Pmelia, &c., it is very wide and conspicuous; m

^ Plat. X.Fu. I.e. ^ Plat. XXVIH. Fio. 6-8. rf'".

EXTERNAL ANATOMY OF INSECTS. 599

Cossyphus it stands out a little from the abdomen, so as
to form a kind of fence round it. Its shape generally ap-
proaches that of a scythe, being incurved and growing more
slender towards the apex ^; but it is sometimes straighter
and shorter. In Geotrupes and many other Lamelli-
corns, the base of the elytrum is nearly vertical, forming a
right angle with the rest of it; it is usually transverse and
straight; but in Calandra Palmarum and many Cassidee
it slants to the scutellum; in Chlamys it is sinuate, and
in Elater it has a deep cavity above the axis which re-
ceives the points of the phragma mentioned before ^.
The ajyex of elytra is usually acute, the angle being,
formed by the confluence of a curving and straight Hne:
but there are many exceptions ; for instance, in Mi/labn's
it is rounded; in Hister obhquely, and in Necrophorus
transversely, truncated; in many Capricorns it is emar-
ginate ; in others, as Man-opus longiinanus, it is biden-
tate; in some Prioni, P. cinnamometis, &c., it termi-
nates in a mucro at the internal angle ; and in Ce7-am'
byx Batus, horridtis, &c., at the external; and, to name
no more, in some species of Necydalis it ends in a long
acumen. The scutellar angle in insects that have a large
scutelJum, as Macruspis MacLeay, is obliquely trun-
cated to admit it, but where it is small it is generally rect-
angular, with the angle rounded ; in Buprestis vittata it
is obtusangular ; and in Di/tisais marginalis, &c., it is
emarginate. In Cassida spinifex, perforata, &c., the hu-
meral angle is producted into an acute lobe that stretches
beyond the head, and in C. bicornis and Taurus it forms
a horn at right angles with the elytrum. Iti general it

' Pi-Axr. XXVIII. Fig. 8. b gee above, p. 582.

GOO RXTEKNAL ANATOLI Y OF INSECTS.

is either rectangular or rounded, with a prominence of
the elytrum within it. The sutural and anal angles exist
only where the elytra are truncated at the apex. In this
case the sutural is generally rectangular, and the anal
ratKer obtusangular or rounded. The Hypodenna is the
fine soft membrane before noticed ^ that lines the under-
side of the elytra, the use of which is probably to prevent
injury to the wings from friction with their usually hard
substance; this membrane is commonly of either a
pallid or brownish colour ; but in some insects, as Sta-
phylinus hybridus, 7mirimis, &c., Buprestis Gigas, it is of
a beautiful green or blue ; and it exhibits the puncta,
strice, and other modes of sculpture of the elytra very
distincdy, the pores of which usually perforate this mem-
brane ^. Just under the shoulders of these organs you
may observe an oblong and sometimes roundish spot,
occasioned by the hypodenna in that part being parti-
cularly tense, and covering a cavity or pocket which ap-
pears to be connected with the axis by the hollow part,
which I regard as representing the Costal Area ; this
pocket is evidently the analogue of a part in the laings
noticed by M. Chabrier S and named by me the ^^z-
alum : from its connexion with the axis by a channel,
this part in elytra should also seem destined to receive a
fluid to add to the weight of the margin and its means of
resistance.

5. Shape. The shape of elytra is various; taken to-
gether, in which case, in describing insects, they are de-
nominated coleoptra, their most common form is more
or less oblong, or forming more or less a considerable

» See above, p. 40^-. ' Ibid. ;}99.

<■ Sur le Vol dc.s- Ins. I c. 4i'8— . c. ii. 325.

EXTERNAL ANATOMY OF INSECTS. 601

portion of an ellipse; taken separately, it ijiclines to that
of an isosceles triangle, with the exterior side curvilinear:
truncated elytra are generally quadrangular, sometinaes
presenting a trapezium, at others nearly a parallelo-
gram, and at others a square. With regard to their
proportions they vary considerably, but the most general
law seems to be that the length shall exceed fwice the
width ; in some, as Buprestis Gigas, it is more than
thrice ; in many Staphylinidce they are as wide as they
are long and sometimes vnder ; they are generally nar-
rower at the apex than at the base, but in some species
of Lycus, as L.fasciatJis, &c., the reverse takes place ; in ,
Telephorus they are nearly of the same width every
where : with regard to their surface they are sometimes
very convex, as in Moluris ; at others very flat, as in
Eurychora, Misy &c.

6. Appendages. These, though not so remarkable as
those of the head and prothorax of beetles, ought not
to be overlooked. In many Capricorns, as Lamia Tri-
bulus, speadifera, &c., the disk and sides are armed with
shoi-t sharp spines ; in others (Stenocorus, &c.) the sutu-
ral and anal angles or one of them terminate in a spine
or tooth; sometimes the whole surface, as in Hispa atra,
&c., is covered, like a porcupine, with a host of slender
spines, or its sides defended by spinose lobes, as \nH.eri-
7iacea : the humeral prominence is armed with a spine
pomting to the head in Macropus longimanus, and form-
ing a right angle with the elytrum in some Curcidionida:,
as Rhynchites spinifex ; but the most remarkable ap-
pendage of this kind is exhibited by Cassida hidens and
Its affinities,— from the centre of the sutures of the elytrum
rise perpendicularly a pair of long, slender, sharp pro-

G02 EXTERNAL ANATOMY OF INSECTS;

cesses internally concave, which both apply exactly to
each other, so as together to form a single horn which
rises, like a mast from a ship, from the body of the ani-
mal ^ Besides the appendages here mentioned, the
elytra exhibit a variety of tubercles and other elevations
of various form and size, which it would be endless to
particularize.

7. Sculpture. The sculpture of the organs in question
is very various and often very ornamental : but as al-
most every kind of it will be noticed in the orismologi^
cal tables, it will not be necessary to enlarge upon it
here, especially since I have endeavoured upon a former
occasion to explain how it may be useful and important
as well as ornamental to the animal^ I shall therefore
only notice a few instances, amongst many, in which
a particular kind of sculpture distinguishes particular
tribes. Amongst those that are Predaceous the Cicin-
delidce have elytra without striae or furrows, while the
majority of the subsequent terrestrial tribes of this sec-
tion are distinguished by them: the Dyjiastida m the
Lamellicorn section are remarkable for a single cre-
nated furrow next the suture; in the weevil tribes the
numerous species of the genus Apion are ornamented by
furrowed elytra with pores in the furrows, which give
them the appearance of neat stitchmg ; in many of those
beetles that have soft elytra, as the glow-worms {Lairir
pyris), the blister-beetles {Cantharis, Mylabris\ and still
more in (Edemera, two or three slight ridges generally
run longitudinally from the base to the apex, and are
visible also on the under-side; as the furrom probably

* Oliv. Ins. No. 97. Cassidd, I- I f. 10.
i> See above, p. o!)/— •

JiX'ltKNAL ANATO.My Dl- iN.Si;CT«. fj03

lighten a Aatd elytruin, lljese rklges may serve to
strengthen a so// one, and it h by these tliat the first ap-
proach is niade to the reticular structure of legmina or
the wing-covers of Orthopiera: Ia/cus palliatus, &c., in
its elytra exiiibits a direct resemblance of tlie reticula-
tions of nervures.

8. Cloi/iing. To what I liave before said on UjIs
subject in general * I slmll here add a few remarks,
which, though they more properly belong to idyLra^ may
ill many cases be extended to the whole body of a l>eetle.
Ill various instances it happens that the beautiful mark-
ings oi" these organs, as in Muaojms I/mgimanm, whose
elytra when denudetl are black, are produced by short de-
cunjl>ejit hairs; in some these variegations arc the effect
<A scales resembling those of Lepidoptera, often of a
metallic lustre; from these scales is derived all the bril-
liancy of tlie diamond-beetle {Enlimm imperialism Germ.);
in some the scales are so minute as to resemble the
}K>llen oi" flowers, as the white marks observable on the
green elytra of the rose-cliafer [Ceionia aurala).

9. CoUmr. The organs of flight in the majority of
the Orders with respect to cokmr are usually the most
gaily deajrated part of insects; I therefore deferred the
notice of that subject till I came to treat of them. In
general the c^^Lour of insects is either inherent in the
substance of their crust, or produced by the hairs or scales
tliat either partially or totally cover it. To confine my-
self to the Coleoplefa, of whose elytra we are treating, it
may l>e observed, I think, in general, tliat the majority of
those that feed upon jnUrescent substances, the sapro-
j/hagous tribes of Mr. W. S. MacLeay, are conjmonly of a

' Sec above, p. '-WJ — •

60*

EXTEUNAL ANATOMY OF INSECTS.

more dark and dismal aspect and colour than those which
feed upon such as are living and fresh, denominated thale-
rophagous by the same learned author ; this you may see
exemplified in his Scarahceidce and Cetoniada^. Again, in
the Predaceous beetles a smilar contrast of colours is often
observable. How brilliant and gay are the fierce Cicindela !
those tigers of insects, as Linne calls them ; how black
as to colour, how horrible in aspect is their near relation
the Manticora : what difference exists in the economy of
these animals is not known, except, as I learn from Mr.
Burchell, that the latter is subterraneous, whereas the
former seek the sunbeam and fly rapidly. I shall now
point out a few instances in which the colours of their
elytra distinguish tribes or families. Amongst the Pre-
daceous beetles a large family of the Cicindelida are
distinguished by a middle angular white band, and se-
veral white dots on their green or brown elytra, as in
a sylvatica ; a family of Brachinus, and the majority
of Mylabris, Lamia capensis and fasciatus, &c., by
black elytra, with yellow or red bands; Carabus violacea
and affinities by the violet margin of these organs ; Cal-
Uochroma Latreille by their sericeotis, and Eumolpius by
their metallic, lustre. These instances will be sufficient
to turn your attention to this subject, which though not
of primary importance in discriminating genera &c., is
not without its use in a secondary view.

10. Uses. I must not quit this subject without saying
something upon the ends which elytra seem designed to
serve. Their first and most obvious use is the protection
of the wmgs when unemployed, that they may not be
lacerated or soiled, and rendered unfit for flight in the
various retreats to which these animals betake themselves

EXTERNAL ANATOMY OF INSECTS. 605

either for food, repose, or to lay their eggs ; to promote
this pui-pose more effectually, the wings are usually cu-
riously folded and laid up under them; and where the
elytra are very short, as in the Staphylinidce, these folds
are very numerous and complex. In some instances,
however, as in MolorchusY., Atractocerus, &c., the wings
are only partially protected by the elytra and not folded
under them ; probably they are less in danger of laceration
from their peculiar habits than the generality. Another
use is to protect the upper-side of the alitrunk, which for
reasons before assigned is usually softer than the under-
side, and also of the abdomen, often above nearly mem-
branous, from the injury to which they would otherwise
be exposed ; in the latter part also the spiracles in Co-
leoptei-a are not covered by the inosculations of the seg-
ments, as is the case in most other Orders, and therefore
probably require some covering when the insect is not
flying. In the Apterous beetles this appears to be their
principal use ; where these organs are connate, or as it
were soldered together, the back of the abdomen is a
thin membrane ; the appearance of tisoo elytra in these
cases is given, doubtless, for the sake of symmetry and
beauty, a subordinate attention to which may be traced
in all the works of creation. If we consider the bulk and
weight of many flying beetles, we may imagine that they
want some assistance, more than the extent and dimen-
sion of their wings seem to promise, to support them in
the an-, and to enable them to move more readily in it;
and although it seems clear from the state of their mus-
cular apparatus that elytra do not move much in flight,
yet by giving a broad and concave surface to the air," for
then they are usually nearly vertical, tliey may assilt iu

606 EXTERNAL ANATOMY OF INSECTS.

some measure as sails, and help them in flying tra-
versely and before the wind ^

ii. Tegmina ^ By this name the learned lUiger has
distinguished the upper organs of flight of the Oi'tho-
ptera and Heteropterous Hemiptera ^. They may be
considered under the same heads nearly as elytra.

1. Substance. Tegmina differ very materiaUy from
elytra in their substance, being generally more or less
diaphanous, though in Blatta Petiveriana the dark parts
are as opaque as elytra, and those of the Mantes that
resemble dry leaves are only semidiaphanous. These
organs are also of a less dense substance than elytra,
something between coriaceous and membranous, which 1
shall express by the term pergameneous, as somewhat re-
sembling parchment or vellum. Another circumstance
relativeto this head also distinguishes them,— they are not
lined with membrane. In some instances, as in B. Petive-
riana just named, they approach nearly to the substance
of elytra, and in B. viridis, some Mantes, and Tetttg07iza,
&c., they are little different from wings in their substance ;
but this does not diminish their right to be considered
as tegmina, since their structure is altogether the same.

2. Articulation with the tnmk. I observed above that
the axis of elytra may be regarded as formed oUkree
parts, one appertaining to each of the areas or their re-
presentatives<i; in tegmina, and indeed in wings m gene-

•a M Chabrier says that the arc described by the 7viugs of Melo-
lontha vtdgaris to that of the elytra, is as 200 to less than 50. Sur le

Voldcslns.c.i.^^^.
" Plate X. Fig. 2. and XXVIII. Fig. 1 8-20.

Maeas. 180(5. Terminohgie der Insekt. 18. Wo.
" Plate X. Fig. 2. is the tegmen of a BMfa divided nito areas.

EXTERNAL ANATOMY OF INSECTS. 607

ral, these parts are separate and may be more distinctly
traced, the axis of the Costal Area being generally the
longest, and that of the Intermediate often the shortest;
these axes are suspended in the wing-socket by elas-
tic ligaments, intermixed with hard bony plates, the
principal one of which, called by M. Chabrier the hu~
mei'us^, is connected both with the tegmen and the
trunk, and in some a little resembles the head and neck
of a swan. This structure permits die anunal to move
the lateral areas in some degree separately, so that each,
especially the anal, shall form an angle with the inter-
mediate ; as the motion of the latter is not wanted, its
axis often falls short of the base, or is obsolete, as in
Blatta,

3. Composition. Tlie three areas, traces of which we
had discovered in elytra, are particularly visible in teg.
mina. If you take any cockroach {Blatta\ you will at
first sight see that in it they are divided into three larger
portions by stronger nervures or folds; and if you also '
take a Mantis, or Locusta Leach, a Fulgora or Tettigo-
nia, the same circumstance will strike you, only you will
see that in these the intermediate portion terminates also
m an axis ; these are what I call the three areas. The
external one or Costal is usually the longest and nar-
rowest^• the Intermediate one is commonly triangu-
lar, with its inner side curvilinear- and the interior
one, or Anal area, in the Chtlioptera is rather oblong;
m Fulgoi-a angular, and in Tettigonia it presents an
isosceles triangle; with its vertex to the apex of the
wmg'J. The first of these may be defined as that por-

le Vol dcs In., c. ii. 327-. - Pj.atk X. Frc. « b-

608 EXTERNAL ANATOMY OF INSECTS.

tion of the whig that Ues between the costal and posl-
costal nervures; and perhaps, in some cases, ^smMantis,
for there is the fold of the tegmen, the mediastinal may
be re-arded as its hmit ; the Intermediate Area is that
which^ies between the postcostal or mediastinal nervure
and the anal fold of the wing; and the Anal Area is the
remainder. These areas may perhaps best be made out
by tracing each to its axis. To study them carehiUy m
iegrnina and hemelytra is of considerable importance;
for in them we find the first outline of the general plan
upon which the wings of insects are constructed, and
which, as we shall see hereafter, more or less enters into
the composition of them all.

4. Position, and folding in repose. With regard to
their position when not expanded, tegmina vary some-
what in the different tribes. In the Coleoptera we have
seen that, except in a few instances, the elytra umte at
their suture. Something like this takes place m F^lgora,
Cercopis and affinities, in the Homopterous Hemptera;
in these, though the union is not near so exact, yet U e
do nStlap over each other; they are usua ly
nTore or less deflexed, with scarcely any portion m a ho-
rizontal position: m Tettigonia F., aiermes, Aphis, ^
the middle part only of these organs meets, from wh.h
point they diverge both towards their base and apex •
In the Ortkoptera the position is quite ^1^^^^'/;;/;
tegmen more or less lies over the other. In BMU.,^n^

which the tegmina are nearly horizontal, the left hand
which r a ^^^^ ^^.^^^g

one covers almost halt the otnei

the Order, with httle variation, the Anal Area of the teg

... . „o " PtATF. X. Fig. 2.

» Stoll, Cisates, L vm. /. .59.

EXTERNAL ANATOMY OF INSECTS. 609

men is horizontal, and covers the back of the animal, and
the Intermediate and Costal are vertical and cover its
sides; the former, however, in some cases, only forms the
angle between them. Sometimes in these the right-hand
one is laid upon the left, as in Acheta; and sometimes the
reverse of this takes place, as in Acrida K. With reo-ard
to the folding of ihetegmina, the most remarkable instance
that occurs is that of Acheta monstrosa, in which the ends
of both these organs and the wings, in repose, are folded
like a fan, and then rolled up like a serpents

5. Shape. The shape of tegmiiia is various. In the
Blattje and some Ma^ites they are more or less oblon<r .
in Mantis precaria, strumaria\ and others, they incline
to elliptical; in Phasma Gigas and Acheta monstrosa they
are vath^v panduriform^ , M. gongyloides they are
semi-cordate^, in Pterophylla trapeziformis they are
rhornboidal^; in Conocephalus erosrcs they are sinLted •
in Locicsta Leach they are usually linear or linear-obl
long^ m Pta-ophylla K. they generally terminate in a
short mucro^; and in some of those Mantidce whose
tegmma simulate arid leaves, in a recurved one " In
the Homopterous Hemiptera the shape of these orc^ans
IS less various. In the Fulgorellce Latr. they incline to
a trapezium, sometimes to a pentagon in tlie Tet
tigonice F. they approach to an obtuse-angled trian-

StoU GrUlom t. i. c./.2. i. ikuI , ,

f c» It ri V veined like leaves.

S o IM L VI a./. 18. and Plate XXVIIF. Fig. 19.
Stoll Sauterd. d Sabr. t. h r,,:j ^„ , * .

' Ibid. Ci,al.., If. 1, 3-5. Z , vi./.31 • ""'-^
VOL. III. 2 II

610 EXTERNAL ANATOMY OF INSECTS.

gle; and in others of the tribe they are nearly wedge-
shaped M • 1

6 Neuration. The circumstance that most strikmgly
distinguishes tegmina from elytra is their neuration or
veining ; which adds much to their strength, without m-
creasing their weight so much as to render them unapt
for flight. To look at these organs in Blatta Petiveriana,
you would imagine them at first to be deprived of this
distinction ; but if you observe them attentively, particu-
larly their white spots, you will soon detect their ner-
vures; and if you further examine their lower surface,
you will find them very visible. The gibbous BlattcB
also, Blatta pida and affinities, the analogues of Erotyhis
amongst the Coleoptera, have tegmina which, except at
their apex, exhibit but faint traces of the nervures of their
tribe, and approach to elytra besides by the innumerable
minute impressed points that cover them. In the Or/y^o-
.^.raandsomeHomopterousffmz^^^rathenervuresmay

be divided into longitudinal ones more or less ramified,
and traversing ones. In the Blattc. the traversmg ner-
vures cut the longitudinal ones nearly at right angles, but
not at regular intervals, so as to cover the tegmen with
quadrangular areolets; in Mantis precaria and affinities
the longLdinal nervures of the Anal Area diverge from
the base, and are traversed nearly as in Blatta. while
those of the Costal diverge from the mediastinal nervure,
but the traversing ones form innumerable irregular re-
ticulations; in Mantis sinuata K.^ the whole tegmen has
such reticulations but less numerous ; m Loa.ta Leach
it is regularly reticulated at the base, but the areolets of

a Stoll Cigales t. m.f- 12-15; and t. xvii./. 92.
h Linn. Trans, xii. 449, no. 96.

EXTERNAL ANATOMY OE INSECTS. Gil

the apex are quadrangular; in the Marites, with oblong
wings, all are quadrangular; in Pterophylla K. the
longitudinal divergmg nervures are not numerous, and
the traversing ones cut them into quadrangular and tri-
angular areolets, besides which tliey are covered by in-
numerable impressed pomts, so as altogetlier to exhibit
a most exact resemblance of the leaf of some evergreen :
m Gt-yllotalpa the longitudinal nervures of the Anal Area
rather converge towards the apex, are traversed by few
transverse nervures, and those of the Costal Area which
diverge from the mediastinal nervure by still fewer; the
neuration oi Acheta F. has beep before described''; I
shall only observe here, that the constructors oi stringed
instruments of music might, perhaps, from the tegmina
of the male, the nervures of which probably modulate
the sounds which it produces, take a hint for giving the
strings in them a serpentine or convolute direction, and
so might produce something new in that department,
corresponding with the serpents and French-horns in
•wind instruments. Of the Homopterous Hemiptera in
the FulgorellcB Latr., which are most analogous to the
Orthoptera of all that tribe, the longitudinal nervures are
more numerous and branching, more especially toward
the apex of the tegmen, and are traversed as much by
transverse ones, sometimes reticulating the wing with
roundish areolets, as in F. laternaria, and at others with
quadrangular ones, as m F. candelaria-, in some of these
however, as Otiocerus K., Flata F., &c.^ there are no
traversing nervures ; and these lead to the Cercopida
and others in which the longitudinal nervures become

' Vol. I. p. .395 -.

" Linn. Tram. xiii. t. i./. ] 4. Flata should come before this genus

2 R 2

612 EXTERNAL ANATOMY OF INSECTS.

few, and some are without any% and these terminate
those of this section of the Order in which the nervures
in question are continued to the margin of the wmg. We
next come to those, Darnis, Centrotus, Membraas, &c.,
in which they are circumscribed a httle within the apex by
a traversing nervure, so that the tegmen ends in a margm
of pure membrane, and thus some approach seems to be
made to the Hemelytra, from Tettigonia, the most con-
spicuous genus of this tribe, in which the areolets, few m
number, hke those Lepidoptera, are not formed, except
the terminal ones, by traversing nervures, but by the
ramifications of the longitudinal ones ; in Chermes the Li-
termediate Area, which is connected with the base of the
wing by a single nervure, is the only part that has any

areolets ^. 1 1 i

7. Colour. Orthopterous insects are seldom remark-
able for tegmina of brilliant colours; there is in them none
of that gilding or metallic lustre which so often distm-
guishes elytra: they are alsofi-equently less ornamented m
this respect than the wings, with which they usually form
an agreeable contrast. Their reticulations and nervures,
which are sometimes of a different colour from the i-est
of the tegmen, decorate them considerably: a remarka-
ble circumstance belonging to this head attends the black
tegmina of Blatta Petiveriana ; one has>z.r white spots,
and the other only three; but as one laps over the other,
the symmetry of the arrangement is preserved : the Ho^
mopterous Her^piera are more distmgmshed m t ns
spect, and some of the mgorid<. imitate the Lep^dopt.. a
both by their ocelli and spots: Fulgora laternarra. Can-

=. Of this kind is one of Stoll's Ggales, i. xxv./. HI.
b Plate XXVIII. Fig. 18.

EXTERNAL ANATOMY OF INSECTS. 613

delaria, serrata, and Diadema, sufficiently exemplify this
remark, as do several Flata likewise

We may observe here— that tegmina are more calcu-
lated for flight than elytra, both from their thinner sub-
stance, and from the angle that their Anal Area, and often
the Costal, forms with the rest the tegmeu; a circum-
stance which, m wings, M. Chabrier thinks presents some
faciHties in that Idnd of motion.

iii. Hemelytra The next species of wing-covers,
which though varying in the substance of then- base, ter-
minate in a part distinct from the three areas, consisting
m almost every case of mere membrane, peculiar to the
Heteropterous Hemiptera, are called hemelytra, or half-
elytra:— this term was also formerly employed, but cer-
tainly incorrectly, to denote tegmijia. I shall consider
them with respect to such of the particulars noticed under
the former heads as apply to them, but without repeating
them formally.

1. Astotheiv substa7ice, they must be separately consider-
ed withregardto their baseand apex. In various instances
the base, or part consisting of the three areas, is almost
corneous, as in CydmcsMm-io andbicolor, bugs not uncom-
mon with us, and many others «=; in these cases it is lined
with a hypodervia like elytra; and in many the points,
which are impressed upon it, also perforate the liemely-
trum, and seem to act as pores: but in Lygcmis, Rcduvius,
Capstis, Miris, and the majority of the Heteropterous i/e-
7ntptera, the organs in question being soft and flexible,

StoU Cigales t. x.f. \, t,x. f. 46. t. xxix. /. 170. t. v. /. 22. t. iv.

•^\ t t'' -n, , " Plate X. Fig. 3.

m Latreille s whole genus Penlaioma, including several Fabrician
genera, the are more substantial than in the subsequent

614? EXTERNAL ANATOMY OF INSECTS.

may be stated as rather resembhng leather than horn ;— on
this account this part of a hemelytrum is denominated the
corium. In Scutellera the portion covered by the scu-
tellum is membranous; and in Acanthia jparadoxa, and
the cucuUated species of Tingis, the wing-covers are en-
tirely so. The apex of these organs is almost universally
either membranous or coriaceo-membranous, on which
account it is called the memhrana. I say almosU because
in Aradus and the HydrocariscB Latr., this part, though
rather thinner than the rest of the Hemelytrum, is also
coriaceous ; in the latter tribe usually with a very narrow
membranous edge; and in many Bednvii and Zeh there
is scarcely any difference in the substance of tlie base and

apex. ,

2. As to the articulation oiHemelytra with the truuK, it
seems not strikingly different from that oi tegmina :
point or base of the Intermediate Area, which falls short
of that of the lateral areas, seems connected by a slender
ligamentous piece, with its axis, which is thick; and I do
not discern Chabrier's humerus shaped hke a swan's head

and neck * r u * f

3. The composition o^the^e organs differs from that ot

tegmina in more respects than one : in the first place U.ey

consist, as was lately observed, of instead of three

areas; in the next, they appear to have, at least severa

of them, a part, which I suspect to be analogous to that

above described in Coleoptera, supposed to represent the

phiahm of wings^ I shall first speak of the areas. In

some apterous species related to the bed-bug, Lyg^us

brevicollis Latr. % &c., there is no trace of the usual areas,

c u rnj Ibid- P- 600.

: ^riS";,ear.yre.e,„b.e, the Coleopterous ge,„. a.,-

EXTERNAL ANATOMY OF INSECTS.

615

and the memhrana is a very narrow strip ; in L. apterus
the former are very faintly traced out, but they are pre-
sent in all those that are furnished with wings ; whence
we may conjecture that they are of the same importance
in flight with the folds observable in those organs ^ The
three basal areas may be said most commonly to present
three isosceles triangles, the Costal one being narrow and
curvilinear die Intermediate the most ample % and the
Anal one the narrowest and shortest with its vertex to-
wards the apex of the Hemelytrum^ while in the two former
it is at its base. In LygcBus compressipes {Bhinuchus
K. MS.) the Anal Area is cultriform; and m most of the
Hydrocorisce it has an angle in the middle of its posterior
margin. The proportion that the memhrana or apical area
bears to the rest of the wing varies in the different tribes.
In some, as before stated, it is obsolete, in others nearly
so ; in the majority, perhaps, it occupies about a third of
the hevielytr-um in Lygoeus compressipes, cruciahcs, &c.,
full half; m Alydus calcaratus, two-thirds ; m Reduvius,
nearly three-quarters'^ : and m Aradus depressus the cori-
um,— divided, however, though indistinctly, into tlie three
areas,— is driven to the base of the wmg : two ends are
answered by this structure— as this insect Uves under
bark, its thm hemelytra take less room ; and as it flies,
though it has only rudiments of wings, they are more fit
to supply their place : the part we are speaking of usually

Ion Latr., agrees with Latreille's description in all respects, except
that It cannot be said to be vieml)rana nulla apicali.

" Chabricr Amlyse, &c. 24. Plate X. Fig. 3. b\

' Ibid. c. ^ .1 Ibid, d:

Plate XXVIII. Fio. 23 /"' is the corium. and g" the membrann
of a species of Reduvius F.

616 EXTERNAL ANATOMY OF INSECTS.

runs obliquely from the vertex of the Anal Area to the
base of the Costal.

4. As to their j)osition andf aiding in repose, Hemelytra are
usually nearly or altogether horizontal; but in Notoneda
andPZm they are dejlexed and cover the sides of the body;
and the apical area of one wing precisely covers that of
the other ; where the scutellura does not intervene, as m
Scutellera, Pentatoma, &c., the vertical angles of the Anal
Area meet in the middle of the back, so as to exhibit
the appearance of a cross. In Notoneda, in which the
hemelytra are deflexed, at the apex of the memhrana is
a fissure which permits the two sides to form an angle
with each other, and to apply exactly to the body. In
Plea, in which there is no apical area, the posterior
margins of the tegmina, as they ought rather to be term-
ed, unite, but do not lap over each other. With regard
to the appearance of something like a phialum, if you ex-
amine the hemelytra of most species of bugs on the un-
derside, you will see that the costal nervure at the base
is inflexed and covers a kind of channel ; if you next take
one of Belostomagrandis, where the structure is most con-
spicuous, or even the common Nepa cinerea, you will find
in the same situation, adjacent to the inflexed costal ner-
vure, a hollow tube running from the base of the wmg,
and terminating, after proceeding about one-fourth of its
length, in a hollow cavity, which, as it is covered by a
membrane, appears tome to be a collapsed pouch. This
circumstance is worthy of further and more general in-

vestigation.

5. In their shape, with few exceptions, hemelytra more or
less represent a wedge, being wider at their apex, where

EXTERNAL ANATOMY OF INSECTS. 617

they are usually obliquely truncated, than at the base ;
but in Plea Leach they are obtusangular, with the angle
in the sutural margin ; in Notonecta^ on the contrary, an
obtusangular sinus distinguishes that part; in Nancoris
tliey are curvilinear and every where of equal width ; in
Itanatra they are linear and straight ; in Aradus they
are oblong, usually with an external lobe or dilatation at
their base: a remarkable instance of the intention of this
is observable in a nondescript Brazilian species, in which
the head, prothorax, and abdomen, are edged with a
number of broad foliaceous appendages ; if the base of
the hemelytrum had not been furnished with a similar
appendage, the symmetry of the whole body would have
been destroyed by the hiatus between the prothorax and
abdomen, as may be seen by removing the /imc/7/i?m but
by this compensating contrivance of Providence, the gap
is filled, the above lobe fitting exactly into it.

6. The «e^^^•a^^■o;^ of these organs will not occupy us long,
since the cwium or harder part, though in some species
there are traces of nei-vures, is often without them. Those
of the cucullated species of Tingis resemble many tegmina
in being ornamented by them with a kind of network,
which looks like the finest lace; in several Lygcci, Edessa,
and some Reduvii, there are a few diverging longitudinal
nervures which occasionally by a ramification here and
there form an areolet^ but there are seldom any tra-
versing nervures. The Apical Area is usually most di-
stinguished by nervures, in some forming several areolets,
as m Aradus, in others running parallel to each other,
nearly to the end of this area, as in Belostoma grandis,

Vlxtv. XXVllI. Fig. i'^.

618 EXTERNAL ANATOMY OF INKECrS.

where they are met by a traversing nervure ; the object
of this is doubtless to strengthen the membrane.

7. Both tegmina and hemelytra are most commonly
naked, yet very short hairs are found on those of some
species of Cercopis, and in many more instances in those
of the latter description, as in Notonecla, several Li/gcei

and Reduvii, &c.

8. Colours in hemelytra are very various, and m many
instances are peculiar to families ; in certain Lyg^ei {L.
Hyoscyami, &c.) black and red; in Lygcsus compressipes
and affinities a dingy black ; in some Reduvii black with
a large white spot ;-but it is needless to enlarge further

on this subject.

9 That hemelytra are used in flight is evident not only
from the large space allowed for their muscles % but like-
wise from a circumstance noticed by M. Chabrier, that
in flight, in the Pentatomce Latr., the corium of the he-
melytrum is fixed to the wmg-, in which case both must
describe the same arc.

iv Win^s. We are next to consider organs which are
exclusively" appropriated io fight, and therefore are pro-
perly denominated ^ings. These in the Orders that have
elytra, tegmina, or hemelytra, are the pair that correspond
^4h the secondary wings of the other Orders. It may
be said, indeed, that in several instances both tegmura and
hemelytra do not diff-er at all in substance or use from the
wings that they cover. This is true; but as tl^.r struc-
ture in other respects is the same with that of those that
are more solid and less apt for flight, it was convement to
consider them under the same name.

■» Chabrier Analyse, &c. 23.

liXimilSAL ANAJOMY OF JN;iEC'lK, Ql<J

1. To begin with tlie arlicutation of thuHc. oygans voUh
the Lrunic ; in general it njay be «taUi<l that thiii, a« in
tcf^mijia and hemdijlra^ \n uaymWy by tlie intervention of
three axes, formed by the conflux of the nervures of the
three areas at the ba«e of the wing, which either imme-
diately or by other pieces are implanted in die trunk, m
as to rea;ive from it the aerial and oUier fluids, neces-
sary for its expansion and motions". Having given this
general statenjent, I shall next apply it U> the wings in
some of the diflcient (Jrders. Jf you carefully extract one
from tlie stag-beetle {LmanusCervus) or any large species
of the Dynustida:, in the Colmplera ; tlie first thi/ig that
will strike you, upon exanjining the base, will be Uiephite
before me/itioned called by Chabrier the humerus^ which
is a str)ut transverse corneous piece, with a deep sinus U>-
wards the wing, filled with ligament: if you again fbllow
the costal, mediastinal, and postcostal nervures, you will
find theni unit<i Uj fbrm an axis, wjnsisting of three pa-
rallel pieces, which connects by its hitermediate internal
pieaj with one end of tliis plate. The nervures of the In-
termediate Area terminate ah>o in a corneous axis at a
greater distance from the base than the otlier two, which
connects with Chal;rier's humerus by means of the liga-
ment of the sinus just named. Those of the Anal Area
are received by a ligament attached to a transverse plate,
widest at its anterior end, which connects with the poste-
rior part of the said humerus; and at its posterior end is
umu;d lf> the poslfrcenum^, with which it fbrms a right
angle. In tlie Orlfioplera Order the structure is not very
diflbrent, but the axes and other plates of the base of the

«= (;habrier Sur k- Vol da Iru. c, ii. .m— . and .326. Note 1.
See above, p. .072 — ,

620

EXTERNAL ANATOMY OF INSECTS.

wino- are less distinct and rather cartilaginous ; the ner-
vures of the Anal Area often terminate in a transverse one
that there forms the segment of a circle*; the inner base
of this circle is ligament connected with the jpostfrcEnum^ .
In the Homopterous Hemijptera the three axes may be
readily traced, but the humeral plate, with which they all
are connected, is more irregular in shape, and in Fulgora
longitudinal, with an angular surface ; in this Order the
nervure, in some cases consisting of cartilaginous rings
in which the franuvi and postfrcemim terminate in the
tegmina and wings, is attached posteriorly to the ligament
of the Anal Area. In the Heteropterous section the three
axes are evident, but the A^wz^raZ plate is not easily made
out. In the Libellulina the axes of the Costal and Inter-
mediate Areas are the coloured broad plates at their base,
formed by the dilatation of their nervures ; that, however,
of the Anal is not dilated, but forms one nervure, in the
primary wing, with ihefrcenum, and in the secondary with
the postfrcemim. Having given you this clue to trace the
axes in those tribes in which they are most conspicuous,
it will assist you in searching for them m the remain-
ing Orders, in all of which they may be traced, except
perhaps in those minute Hymenoptera whose wings have
solely the costal nervures ; probably in these there is only
one axis. In the Lepidoptera and Hymenoptera a cir-
cumstance connected with the present head is observable,
which is not to be discovered in the other Orders: these
are the tegulcc or base-covers, which appear intended to
defend the base of the anterior wings. They are con-
cavo-convex scales, which in the Lepidoptera are large

- Plate XXVIII. Fig. 9. a. " Sec above, p. 572.

•■■ Ibid. p. 560. and Plate XXVIII. Fig. 11. a.

EXTERNAL ANATOMY OF INSECTS. 621

and of an irregular shape % but in the Hymenoptera are
smaller and semicircular''.

2. Wings, with regard to their mhstance, may generally
be termed membranous ; but they vary in this respect, some
being much thicker than others, ^i\h%x partially ox total-
ly: in spotted wings, as in those of many Libellulina,
TettigonicB F., &c., the dark opaque parts are denser than
those that are transparent: in several Orthoptermis m-
sects, as in Phasma, some Mantes, &c., the Costal Area
or covering part of the wing is of a substance equally
firm with that of the tegmen. This is a compensating
contrivance, that where the latter is shorter and smaller
than the former, its membranous part, when folded, may
be protected from injm-y. Another similar contrivance
of Divine Wisdom is exhibited by those Pterophyllce
K. {Locusta F.) whose tegmi7ia resemble the leaves of
plants (P^. Wj/o/m, &c.); in these the tip of the wino-s
when folded being longer, is not covered by the tegmina,
and therefore exposed to injury; to prevent which this
small piece, while the whole wing, as far as covered by
those organs, is membranous, is of the same substance
with them^ The wings of most Coleoptera, Orthoptei-a,
Hemiptera, and Thei-eva coleoptrata, in the Diptet^a, &c.,
are of a firmer substance than those of the other Orders;
in many Loctistce Leach, Fulgora, &c., they are nearly as
firm as the tegmma; and in Ascalaphus italicus, except
at their base, the secondanj wings are less membranous "
than the primary. M. Chabrier has observed ^ that the
wings of insects in general diminish in thickness from their

; V^- 5- "ibid.F,G.]i.i2.g".

btoU Sauterclles d Sahr. t. iv./. 12. /. vi. r, 21. 8cc.
'' Sur Ic Vol des Ins. c. i. 424,

G22 EXTKKNAL ANATOMY OF INStCTS.

base to their apex, and from their anterior to their pos-
terior margin.

3. I should have had, it is probable, but little original
matter to communicate under the head of the composition
and neuration of wings, had M. Jurine, who has written
so ably on those of Hymenoptera, undertaken a survey of
the organs of flight in every Order of insects: but as his
views were confined to only two of the Linnean Orders,
it is not wonderM that his system and set of terms should
fail where a generalization is necessary; and I may stand
acquitted of presumption and conceit if I attempt to sub-
stitute a system and body of terms more universally ap-
pUcable. Had the plan of this able Entomologist led
him to pay attention to tegmina and liemelytra, then-
division into three longitudinal areas would have imme-
diately struck him; and having acquired this outline of
the greater natural divisions, he would have applied it to
the Orders that have wings only, and having discovered
that it is to be traced in all, the result would have pro-
bably superseded my labors. Had his life been longer
spared, perhaps something of this kind would have been
effected by him; but as he, alas ! is gone, and no abler
hand seems to have undertaken the task, I will do what
I can to give you satisfaction on this subjects You

a The idea of dividing the wing of an insect into largex-^^^^^^
first to have been acted upon in Monogr, Apum Angl. f 1801) m M
those of Hyv^enoptera were stated to consist of three portions v:z
Tast MeLn, Ape. (i. 211.); which mode of dmdn.g them was^
f TkdoDted by M. Latreille (Gen. Crust, et Ins. ni. 226. Note 1.).
The same earl author (Ibid. iv. 239.). with regard to the Drpter^
IpTnear approximation to the plan of dividing wn>gs mto longi-
„ade a n^^J ^PP addition of a basal area, which internipts

EXTERNAL ANATOMY OF INSECTS. G23

have already got a tolerably good idea of these areas from
what has been said upon the subject under tegmina and
hemelytra; but I shall now more particularly state to you
how they are circumstanced in mngs. I shall first ex-
plain the general law as to their limits. The Costal
Area^ is all that longitudinal portion of the wing that lies
between the anterior margin and the postcostal nervure;
the Intermediate Area " is all that longitudinal portion of
the wing that Hes between the postcostal and the anal
nervures; and the Anal Area^ is all that longitudinal
portion of the wing that lies between the anal nervure
and the posterior margin. 13ut there are other helps to
enable you to distinguish die areas in the different Orders.
The Anal Area in all Orders forms the posterior fold of
the wing; in Culeoptera turned underwhen in repose; in
Orthoptei-a folded like a fan; in Lepidoptera, in some
FapilionidcE, forming an arch over the abdomen. Agab,
mBlatta, the Costal Area is distinguished chiefly hy longi-
tudinal n^rvm^s ; the Intermediate by oblique ones; and
the Anal by radiating ones ; and in both this tribe and
the Mantida: this last Area is marked out from the Inter-
mediate by a marginal notch, which is not present in
Phasma, but is found in both sections of the Hemiptera.
In Locusta Leach the notch is between the Costal and
Intermediate Areas : in Phasma the nervures of the In-
termediate Area are branches of the externo-medial, while
those of the Anal, as they do in all the Orthoptera, diverge

^nA Intermediate Area, are here adopted ; but his Internal is chanc^ed
to the ^«a/ Area, for the term belongs rather to the base of

the wing. M.Latreille afterwards rehnquished both these nlL?
N. Diet, cniist. Nat. i. 248 - . ^
J Plate X. and XXVIII. b: i: is the Postcostal Nervure
Ibid, c: n: is the Anal Nervure. c ' ^.

624- EXTERNAL ANATOMY OF INSECTS.

from the base of the wing : in many, as in Pterophylla K.,
the part of the wing lately alluded to, that is longer than
the tegmen, and of the same substance, points out the limit
of the Costal Area ; and in others this part terminates in
a segment of a circle and is dilferently reticulated at the
apex from the Intermediate : in the Homopterous Hevii-
'ptera and the Lihellulina^ in which the areas at first seem
indistinct, they may generally be easily traced byfoUow-
ing them from the axes. The separation of the Costal
from the Intermediate in the remaining Orders seems less
easy on account of the branching of the nervm-es : in the
rest of the Neuroptera and the Lepidoptera, if the poste-
rior branches of the postcostal nervure are not included,
you will have a narrow Postcostal Area, which in most
cases forms an angle more or less prominent, in Corydalis
almost a right angle, with the Intermediate: in Hemerobins
and affinities this part is distinguished by areolets form-
ed by transverse nervures, while those of the rest of the
wing are longitudinal^', but if the posterior branches are
included, the Costal Area will be more ample: a similar
observation applies to the Hymenoptera and Diptei-a; in
these, in all cases, the areolets adjoining the anterior mar-
o-in, which follow the stigma, should be regarded as be-
longing to the Area in question \ In those tribes of the
former Order, whose wings are without nervures, the
areas are often marked by folds.

M. Chabrier has observed that in Coleoptera the spe-
cific weight of the margin of the wing, and its means of
resistance, are augmented by a liquid which is introduced,
at the will of the animal, into a long pocket under the

|> Ibid. KiG.8. !). U."*-

EXTERNAL ANATOMY OF INSECTS.

625

brachial, here called the costal and mediastinal nervures,
covered by a supple membrane, which in a state of repose
becomes flaccid : it is easily detected, being of a paler
colour than the nervures between which it lies ; this is
what I call the Phialum ; we have before seen that it
exists also in Elytra and some Hemelytra^ ; but I have
not detected it in any other wings.

I have before given you a sufficiently full account of
the alulcB or wuiglets of Diptei-a and shall here only
observe that they are not confined to on^ particular tribe,
as has been usually imagined; but though sometimes
extremely minute, simple, and not easily detected, are an
universal distinction of the Order.

Having thus endeavoured to elucidate the larger Areas
into which wings appear to be divided ; I shall next
say something on the smaller ones produced by the in-
tersection or ramification »of the nervures ; these had
been named areolets {areola) several years before M.
Jurine's work, in which he calls them, I think improper-
ly, cellules {cellulcB), was published ; I therefore retain
the pnor term. The general structure of the nervures
of the wings of insects having been before explained", I
shaUnothererepeatwhatlthensaid; but there is a curious
circumstance connected with it, particularly visible in the
wings of certain Hymenoptera, that I must not pass with-
out notice. If you examine attentively with a microscope
against the light the wing of any Nomada or Andrena,
you will discover little transparent points in some of the
smaller transverse nervures that form the middle areolets,
in which the nervure becomes white and looks as if it

Sur le VoLdes Ins. c. I 428. - See above, p. 600, 616.

VOL. u. p. ^58— . See above, p. 559. "i Voi 11 p 346—
VOL. III. 2 s

626 EX'reiiNAL ANATOJIV OF INSECTS.

was interrupted, though h, substance it seems continued:
these little points, somewhat resembhng minute air bub-
bles detained in the tubes, are what M. Jurine, who first
discovered them, has, on that account, named Mice, which
he thus further describes-.-" When the tube (of the ner-
vure) arrives at the spot where a MU is to be formed, it
extends itself on all sides in minute threads in the upper
membrane of the wing, losing its colour and tubular struc-
ture, which it resumes immediately after the fovmaUon
of the bulla"." But if you look closely at them you will
find that there is always a slight fold of the wing that
cuts the nervure exactly at the Wlce, and if the fold
changes its direction they accompany it; their object,
therefore, is clearly to relax the tension so a. to admU a
little motion where the fold is; consequently, rather than
tete (bubbles), they should be denominated articdaUms
A similar construction, but on a larger scale, may be ob-
served in the wings of Coleopta-a^ and some others, as
Psocus, where thefolds traverse the nervures. I shall next
makeafewobservationsontheprincipalneryures;andflist

a word upon their names. M. Jurine, being of opmion
that a striking analogy exists between the wmgs of
and those oUiris, in which M. Chabner seems toag.^
with him, has named the nervures in the "tcr™-
of the wings of the former, radim .ni adntu., as cone
sponding with the bones so named in the fore-arm of the
Ler, :id the plate which often terminates these ne -
vures in H.jn,e.u„te,-a, he names the.a,y,«.. .t may look
like presumption to differ from two such weighty authc.
rities, but as their observations seem to have been too

^ J i h Plate X. Fic. 4.

Jurine Hymenopt. 10. and /. v.

EXTERNAL ANATOMY OF INSECTS. 627

limited, in one case to the Hymenoptera and Diptera on-
ly; and in various Orders there is nothing analogous to
the stigma or carpiis, and all the other nervures of an in-
sect's wing have no analogue in that of a bird, but more
especially as M. Latreille seems to think with me on this
subject % I have retained Linne's term for the marginal
nervure, and for most of the others have adopted those
of the great French Entomologist just mentioned. I
shall here only further observe,-and it seems to me an
observation of prime importance, in the determination of
the question of the analogy of the wings of insects,-that
they are not, as in birds, the fore-leg converted into an
organ of flight, but, like the wmg of the Lh aco, an organ
superadded to the legs; and, further, that the connection
IS not with the fore-legs, but, as has been before ob-
served ^ with the two posterior pairs.

The Costa- is usually the strongest of the nervures,
and that upon which the wing seems to be built ; but in
some cases, as in Blatta, Scutellera, Cynips, &c., it is re-
presented by the mere membrane of the anterior margin •
m some Coleoptera, as m Geotrupes, Dytisms, &c., its struc-
ture, except at the base, appears to be annulai- orneai'ly
so, at least a vast number of corrugations, running trans-
versely, are observable on its upper and lower suifaces •
It IS thus capable of greater tension and relaxation, and
more flexUe. The stigma or carpus ^ though most conspi-
cuous m the Hymenoptera Order, may be traced in some
Coleoptera, Heteropterous Hemiptera, the LibelMina,
&c.; but It has no representative in the Orthoptera, Le-
ptdoptera, Trichoptera, ^c. The mediastinal \s nsn^Wy

" Ibid. Fig. 4,11, „r.

2 s 2

6?8 EXTERNAL ANATOMY OF INSECTS.

very slender nervure, placed between the costa and post-
costa, sometimes terminating in the former % and at others
in the latterly : the Orthoptera, Lepidoptera, &c., how-
ever, and some others, it is a very conspicuous and prin-
cipal one^ in the Hymenoptera it is obsolete, merging
in those nervures <=. The Postcosta is the principal ner-
vure of the wing in Scutellera, but in Staphylinus it is
' wanting; in Chalcis sispes it is the only true nervure of
that organ, the others being represented by spurious
ones The externomedial and mterriomedial are some-
times distinct at their origin, but more frequently are
branches from a common stem.

Having made these general remarks, I shall now con-
sider particidarly the neuration of the wings in the dif-
ferent Orders, beginning with the Coleoptera. The first
thing that strikes the physiologist in surveying a wmg be-
longing to an insect of this Order, is the general arrange-
ment of the nervures which are so placed that the
required degree of tension may be given to every part ot
this organ: thus some are nearly straight ^5 others runm
a serpentine direction ^ ; others areforked with one branch
recurrent and another proceeding onwards others agam
are insulated, or donot originatefrom the baseof the wmg,
or fromother nervures, but are merely placed to strengthen
an open space of if: these nervures are also usually
broader and more substantial than those of the wmgs of
the subsequent Orders. Another striking circumstance
with regard to them is that the nervures form few or no

I I'Tvl r 9 ' ' ' ^ Jurill'e %re;op;.t'v. Gen. 47.

« Ibid. i< IG. ». »• 5 Thid 7H-.

* Platk X. Fig. 4. • ' Ibid. a. o-. Ib.d.m.

» Ibid. ' Jbid. a.

EXTERNAL ANATOMY OF INSECTS. 629

closed areolets, except in the Costal Area, where they
are inconspicuous; m Dytiscus marginalis, indeed, and
Tenebrio Molitor one or two may be found, but in ge-
neral there are none. In many of this tribe the post-
costa, which terminates at the joint of the wing, becomes
recurrent, so as to form a hook, which perhaps repre-
sents the stigma, as in Dynastes ; in Creophilus K., a
rove-beetle, there is no hook but a broad plate adja-
cent to the costa. In the Strepsiptera Order the neu-
ration is extremely simple, the nervures, except one
insulated one, diverging from the base of the wing":
in this respect, as well as in the form of that organ,
an approach is made to the OrtJwptera. In the Derma-
pterathxs approach is still more evident; in the common
earwig % the diverging nervures become numerous; be-
tween each is an insulated one, taking its origin in the
middle of tlie wing, and running to the margin ; a little
nearer to the latter all the nervures are dilated into a
plate; those of the anal area are angular^, and the ex-
posed part of the costal is as hard as the elytra. The
neuration in the OrtJwptera Order may be caUed radiate,
the longitudinal nervures for the most part diverging from
the base of the wing like rays: in some few instances %
but not often, I believe, an insulated nervure intervenes
between each ; traversing or connecting nervures, cutting
the longitudinal ones in various directions, ornament these
wmgs with an infinity of areolets, causing them to resem-
ble fine gauze or beautiful lace or net-work; very often
these areolets are quadrangular, sometimes rhomboidal,

» Ibid. 0'". b Plate II. Fig. 1. Comp. Linn. Trans, xi

'■(Jll^ > ; P«:ATX= X. F.o. 5. <'lbid.«-,o-,;r. "

ntoH Spectres, I. xvui,/. 65.

630

EXTERNAL ANATOMY OF INSECTS.

frequently nearly circular, and differing occasionally, as
has been before observed % in the different areas: it some-
times occurs that there are no traversing nervures'', when
the wing of course is without areolets. In the Hetero-
pterous Hemiptera the type of neuration, as to the wing,
seems borrowed from the Coleoptera, a further proof that
these are the analogues of that Order amongst the Hau-
stellata Clairv. In these the nervures usually are few
and dispersed, and seldom form any closed areolets. If
you examine any Scutellera, Pentatoma, or Lygmis, you
may trace the uncinated, forked, serpentine, and insu-
lated nervures of Coleopterous insects; in Gei-ris and
Velid there is an approach to the neuration of some
Homopterous species, and in Belostoma &c. the wing is
reticulated by sp^crious nervures. In the Homopterous
section there are several types of neuration ; thus the FuU
gorcE resemble the Orthoptera in this respect; while the
TettigonicE F., &c., approach nearer to the Hymenoptera
and Diptera, and have their apical areolets circumscribed
mthin the margin by a traversing nervure; in Plata,
&c., the areolets are mostly formed, not by traversmg
nervures, but by the branching of the longitudinal ones;
in this respect they are not unlike the Lepidoptera. In
this last-named Order there are some variations with re-
gard to their neuration— thus, amongst the buttajlies m
Urania, &c., there is no closed areolet in any of the
wings, and almost all the nervures diverge from the base^ ;
in Morpho, &c., there is only one in the primary wing^;
in Helico7iia, &c., there is one in both wings; amongst

=• See above n 624 " StoU figures Empusa as without

them. t. Lf. 35. but? I have a nondesc. Phasn,a ? ff^^^'l^"^-
'■■ Jones in Linn. Trans, ii. t. viii./. 2. Z^'^-/-

EXTERNAL ANATOMY OF INSECTS.

631

the moths^ in the Bombyces L., this is divided into^wo, and
in Cossus labyrinthicus Don. into three areolets : in some
butterflies {Lycana) there is one insulated nervure*, and
in others (Hespe^-ia) there are two''; in these two last,
and Helicoma, Urania, &c., the end of the Costal Area
is divided into several areolets by oblique nervures*^,
which gives them some analogy to the wings of many
Neuroptera ; and at the base of this Area, in Morpho, is
a roundish areolet''. In this Order the externo-medial
and interno-medial nervures coalesce into one, and are
only represented sepai-ately by their first and third
branches In the Neicroptera Order the general type of
neuration is borrowed from the Orthoptera ; but in Os-
mylus, Termes, &c., there is an approach to that of Flata
in the Homopterous Hemiptera, and in Psocus to others
of that section ; in the second of these genera the ner-
vures, except those of the costal margin, are spurious.

I now come to the Order in which M. Jurine has la-
boured with so much success, I mean the Hymenoptera ;
and I only regret that his labours were directed to so
small a portion of the Class Insecta, and in that portion
only to a part of the upper wing ; I say only a part, be-
cause air those areolets of the posterior part of the wing,
in some cases amounting to jfive ^, that lie behind his cu-
bital cellules, are not employed by him as diagnostics, and
are left without a name. By dividing the areolets of the

» Jones in Linri. Trans, ii, t. viii./. /. •> Ibid.f. n.

" Ibid. f. 2, 3, 6—9. 1 I wonder Mr. Jones's plan of

ascertaining the divisions or subgenera of butterflies by the neuration
of their wings has never been followed up ; it would I think furnish
an easy clue for the extrication of the tribes of all the Lepidoplera.
I mean as subsidiary to more ini{)ortant characters.

' Plate X. Fic. 6. m: ' Ibid. Fig. 8.

632 EXTERNAL ANATOMY OF INSECTS.

Intermediate Area of these wings into three portions, the
basal, medial, and apical^, I have endeavoured to re-
medy this defect, and by naming each set of areolets in
the middle portion, as you will see in the Orismological
Definitions, under the term Areolets, you will find it
easy to describe any given areolet and its place in the
wing ; those of the base may be called the anterior, in-
termediate, and posterior, where three occur; and the first
and last of these terms will suffice where there are only
two ; the apical areolets, or those that are open to the
margin, may be called, first, second, and third in the
order of their occurrence, reckoning from the anterior or

costal margin.

In this Order it is curious to trace the progress of neu-
ration in the wings of different genera. Thus in Psih^
only the costal nervure and the stigma are to be traced'';
in Chalcis the postcostal and stigma^; in Codrus and Leu-
cospis the costal, postcostal, stigma, and a nervure repre-
senting the externo-medial and interno-medial coalescmg
into one^: in Omakis the basilar areolets appear = ; in
Crabro both basilar and mediaV; in Cynips basilar,
medial, and apical^; and in Hylotoma the wing is filled
with its greatest complement of areolets ». The medial
areolets of the Intermediate Area, as you will see in the
definitions, form three distinct series; these may be called
the protomesal, deuteromesal, and tritomesal, reckonmg
from the postcostal areolets; the first of these corresponds
with the cubital cellules of Jurine. These series may be

» Plate X. Fig. 8. basal e; medial/", apical g-.
" Jurine Hymenopt. L v. Gen. 48. *• Il>id- Gen. 4 / .

" Ibid. Gen. 45, 46. Conip. Plate X. Fic. 11.
' Jurine Ibid. Ge.i. 43. ' ZA'rf- Gen. 47.

Ibid. L V. Gen. 40. " ^en. "2.

EXTERNAL ANATOMY OF INSECTS.

633

expressed, according to the number of their areolets; by
figures, the protomesal standing first. They vary much
in this respect in the different genera. Thus in Cyclo-
stoma K. reckoning the didymous areolet as two, the
numbers will stand 4:2:1; m Hylotoma, &c., 3:2:1'';
in Aulaciis, &c., 2:2: 1<=; in Bracon, &c., 2:1:1"^; in
Chelonus, 2:0:1'; in Ci/nips erythrocephahis Jur., 2:0:0*^;
m Formica^ 1:1 :1^; in Oxyhelus^ 1:0:1''; in Chrysis^
0:1:1'; and in Cynips Rubi K., 1:0:0''. The most
natural number is 3:2:1. The next in importance to
the medial areolets of the Intermediate Area are the
apical, or those open to the margin ; the most usual num-
ber of them, excluding the postcostal areolets which be-
long to the Costal Area, is three ,• but in Sirex there is
an approach to four ' in Evania there are only two^j
and in Philanthus there are none " ; in many, as Proso-
pis, Nomada, Andrena°, though there is the usual num-
ber, they are incomplete and do not reach the margin.
The basal areas are of little importance in assisting to
determine genera; they are most commonly iwo in num-
ber, but in Cynips, &c., there is only one p. The shape
and other circumstances of the areolets vary consider-

" This is a remarkable insect belonging to Vespa L., related to the
hornets ( V. Crahro), distinguished by having a semicircular piece taken
out of the internal margin of each mandible, so that when these or-
gans are closed there is a circular orifice,— whence the name Cyclo-
stoma. *> Jurine Hi/menopt. t. ii. Gen. 2. « /^j^, Qrd. ii. Gen. 2.
Ibid. t. iii. Gen. 3. = Ibid. t. v. Gen. 41.

' Ilnd. t. xii. Gen. 40. « Ibid. I. v. Gen. 39.

" Ibid. t.\\. Gen. 29. * Ibid. t. v. Gen. 42.

* This Cynips inhabits a long polythalamous gall of the bramble.

' Jurine Ibid. I. ii. Gen. 11. Ibid. Ord. ii. Gen. ].

" Ibid. t. iv. Gen. 23 ° Ibid. Gen. 30—32,

" Ibid. t. V. Gen. 40

634; EXTERNAL ANA'l'OMY OF INSECTS.

ably in different genera and species: upon these however
I shall not enlarge further, but proceed in the next place
to consider very briefly the wings of the Diptera Order
as to their neuration. These are not so easily made sub-
servient to a general plan. The basilar areolets are now
reduced considerably m length, occupying merely the base
of the wing*; the medial are become less numerous and
important"; and the apical, in a variety of instances, are
the most conspicuous = ; in some wings, as in those of
Penthetria, the Intermediate Area has no nervures or
areolets, or only spurious ones; in Psychoda the nervures
diverge from the base almost without branching, so as to
form no closed areolets d; in many, the lower medial
areolets are very long, resembling the basilar m Hymen-
optera^; these are often crowned by a single small one,
as in the Stratyomidce, Tipula, &c., from which nume-
rous branches proceed to the margin ' ; but in Musca two
large ones approach the margin, the anterior one ha%dng
an angle open to itS; in the Hippohoscida almost the
whole of the wing is occupied by the apical areolets";
though in some cases they are incomplete'.

4. I am next to consider theposition of wings in repose
and their folding. The most important object of this is
that when unemployed they may occupy less space, be
less in the way of the insect, and be most effectually pro-
tected from injury. Another end is also served by this
structure,— that wings can thus be very ample, and pre-

. Plate X. Fig. 12, 15, " Ibid. Fig. 15 /.

c Ibid. Fig. 12. g: " ' Ho. 13.

c Ibid. Fig. 15. c. ' Ibid. d.

« Ibid. Fig. 14. e. " Leach on Eproboscidcous Insecis,

Mem. Wern. Soc. 1817. <• xxv./. 3, 5, 8,&c.
' Jbid. t.x\\i.f. 7, 10, 13.

EXTERNAL ANATOMY OF INSECTS.

635

sent a large surface to the action of the atmosphere with-
out incommoding the insect when it has not occasion to
use them.

With respect to this head, insects may be divided into
two classes — namely, those whose wings in repose are
covered by wing-cases harder than the wings themselves,
and those that have no such protection. In the former
the wings, though the rule admits several exceptions, have
more folds than in the latter. As the different mode of
folding the wings has been assumed for a characteristic
of the earlier Orders, I shall explain to you Avith as much
brevity as possible how each is circumstanced in this re-
spect, beginning as usual with the Coleoptera.

There are tnoo principal folds of the wing in this Order,
which may be named the anal and the apical: the for-
mer is when the Anal Area or part of it is folded on the
under surface of the base of the wing; this fold is always
more or less longitudinal: the latter, the apical fold, is
by means of the commissura or joint of the postcosia lately
mentioned : which in Hister, Staphylimis, &c., for obvious
reasons ^ is nearer the base of the wing ; in NecropJio-
rus in the middle ; in Dynastes Aloeus beyond the mid-
dle''; in Tenebrio Molitor neaxihe apex; and \n Di/tiscus
marginalis there appears to be no joint at all ; but the
fact is, that in this insect the postcosta,— the termination
of which really forms the joint, the costa itself being only
flexible at that point,— stands at a greater distance from
the latter at its end. Well, at this joint the above fold
is made, the apex of the wing, being first folded longi-
tudinally, turning under and inwards, and forming an

' Insects with short elytra of course must fold their wings nearer
the base than those with long ones. Plate X. Fig. 4. d".

636

EXTERNAL ANATOMY OF INSECTS.

angle, more or less acute, with the joint or costal margin,
so that the fold is not quite but nearly transverse : this
at least is the case in Geotrupes stercorarius and other
Lamellicorns : in Stapht/linus, &c., there are several
transverse and longitudinal folds, and thus the wing is
more easily packed under the short elytra; in Molorchus,
Necydalis, &c., in which it is left uncovered, except at its
base, the anal fold takes place, and the apical in some
degree; a short portion near the apex forming an obtuse
angle with the margin ; in Atractocerus the wing appears
to be only longitudinally folded; and in Buprestis vittata
only the anal fold is to be detected. Besides these trans-
verse and longitudinal folds these organs, in many bee-
tles, have an infinity of fine corrugations, which ramify
like thenervures of the tegmina of Flata^, &c., proceeding
from the Costal Area or the disk of the wing to the pos-
terior margin ; the object of these plicatures is doubtless
to present a more ample surface to the action of the at-
mosphere in flight^ When all these folds have been
made in a Coleopterous wing, the apex of the one at its
posterior margin crosses or rests upon that of the otlier^
In the Dermaptera^, at least the common earwig,
there is a triple transverse fold of the wing, and besides
this it has numerous longitudinal ones like those of a fan,
each of the diverging nervures representing one of the
sticks. In the Strepsiptera the folds are only longitudi-
nal ; a circumstance which, besides the form and neura-
tion of the wing, sufficiently attests that its station is more
near the Orthoptcra and Coleoptera than the Diptcra.

- See above, n. 61 1 . " See above, p. 613, and Chabrier

Analyse, &c.2i. ^ Plate XXIII. F,g. 5.

" Plate X. Fjg. h.

EXTERNAL ANATOMY OF INSECTS. 637

We next come to the Orthoptera^ ; in these the folds in
general are longitudinal ; and those of the Anal Area in
particular, either in whole or in part, exact counterparts
of a fan : wherever there is a straight nervure, there is
usually a fold or a tendency to it; this is the case even
with the short oblique ones observable in the Interme-
diate Area of Blatta : in this tribe the Anal Area, or a
considerable portion of it, is folded under the rest of the
wing, and the whole lies on the back of the animal, so
that in this wing there are only two primary folds ; but
in those with a narrower body, as Phasma, &c., there
are more, and the Anal Area, folded like a fan, lies hori-
zontally on the back ; the Costal is vertically applied to
the sides, and the Intermediate is between both, as in the
tegmina^. In Gryllus Latr., Gryllotalpa, &c., when the
wings are folded, the end of the Anal Area projects so as
to present the appearance of two tails ; and in that re-
markable Chinese animal Ghyllus monstrosiis, in which
these tails are very long, they are convolute like those
of some quadrupeds'*. It is to be observed that in the
secondary folds of these wings the angles of the folds are
surmounted by a nervure.

In both sections of the Hemiptera Order, as in the Co-
leoptera, the Anal Area is turned under the wing and lies
over the back of the insect; this is the only primary fold,
but besides there are several longitudinal semifolds or
secondly ones, in which one part of the surface forms an
obtuse angle with another; and in Tettigonia, &c., these
folds ramify in the wings as well as in the tegmina. at the

» Plate XXVIII. Fig. 22. See above, p. 608—.

' Stoll Grillons, t. iii. c. /. 11—13. " Ibid. t. i. c.f. 1, 2.

638 EXTERNAL ANATOMY OF INSECTS.

margin : a number of semifolds also, sometimes trans-
verse and sometimes oblique, run in pairs from each side
of every nervure of the disk of both tegmina and wings in
the genus last named, the use of which has been before
mentioned*.

We now come to those Orders that \i^\efour mem-
branous wings : first, I shall consider the Lepidoptera.
With respect to the position of their wings in repose some
variations take place. In the majority of the day-Jliers
{Papilio L.), when the animal reposes the wings are ap-
plied to each other by their upper surface so as to be
vertical; but in the skippers {Hesperia), the secondary
wings assume a horizontal position, while the primary are
vertical but applied to each other. In the Crepuscular
tribes {Sphinx L.) the upper wings are incumbent on the
lower, and deflexed. In the night-fiers {Phalana L.)
the types of position are various. In some Attacus, Sa-
turnia, Noctua, &c., the wings cover each other, and are
a little inclmed from a horizontal position; in Gastro-
pacha, Odenesis, and some other Bomhycida, they are de-
flexed, and the anterior margin of the under wing pro-
jects beyond that of the upper: in some of the TinecE L.,
as Crambus, the wings are convoluted, and in others,
Galleria, they are applied close to the sides of the body,
and being elevated at the apex, terminate, to use a French
term— queue de coq : in Noctua, Geometra, &c., the
wings usually cover the abdomen, and are nearly hori-
zontal. With regard to the folds of their wings, the
Anal Area of the secondary is tlie only part that has any
striking one; in Papilio Hector and affinities it turns

* See above, p. 636.

KXTERNAL ANATOMY OF INSECTS.

639

up SO as to defend the sides and part of the back of the
abdomen ; in MorpJio Teucer it turns down, and meeting
that of the opposite wing, forms a semitube which re-
ceives and shelters that part below. In the Crepuscular
and Nocturnal Lepidoptera this fold, especially in the
former, is very slight. With respect to semifolds in the
Diurnal, there is one originating in the disk, between each
of the nervures, that goes to the margin of the wmg; like-
wise the under wings, particularly of many NoctucE, Arc-
tic, &c., have many longitudinal semifolds.

In the Neuroptera Order several variations take place
with regard to the ■position of these organs in repose :
thus, in Mshna, Libellula, &c., they continue expand-
ed ; in Argion they are applied to the body ; in Myrme-
leon the upper are horizontally incumbent on the lower ;
in Hemerohius they incline to the horizon. With regard
to their folds in JEs/ma, &c., the longitudinal nervures
alternately form the summit or the bottom of a semifold,
as do those branches that terminate in the posterior mar-
gin ; this kind of plicature may be observed, but in a less
degree, in Ascalaphus, Myrmeleon, &c.; in Panmpa every
nervure is the ridge of a slight fold ; in TermeSy on the
contraiy, it forms its bottom. In the Trichoptera, the
under wing being much more ample than the upper, the
Anal Area forais a fold under the wing, and there seem
longitudinal secondary folds besides.

We now come to the Hymenoptei-a. In this Order
the wings, as to their position in repose, are usually in-
cumbent upon each other, and cover the abdomen; in the
V -spidcE, however, they are placed parallel to the body,
but do not cover it. Before I notice the plicature of
these wings, I must recall your attention to what I lately

64-0 EXTERNAL ANATOMY OF INSECTS.

observed » with regard to Jurine's hullce (bubbles), but
which are really the joints of the nervures, as they are
to be found only where the folds pass; and where they
exist they are an index by which the folds, or rather se-
mifolds, may be traced. I counted eleven of these httle
joints in the upper wing of Andrena cineraria; sometimes,
however, instead a bulla, a nervure stops short to ad-
mit the fold. Wings in this Order have often three
longitudinal seniifolds more or less conspicuous ; these
you may trace in the saw-flies ( Ten/ Wo L.), whose
wings Linne terms tumidcs, by which term he would in-
dicate the elevation of the whole surface produced by this
structure ; in the under wings of these, and Scolia, Bem-
bex &c., the Anal Area is turned under the wing, as in
many preceding tribes ^ : in Sirex, &c., that Area of the
upper wing turns upwards, forming an acute angle with
the rest of the organ; the same circumstance distinguishes
the under wing in the IchneumonidcE. Several apical
semifolds, marked by a pellucid streak, distinguish
Tiphia F., and in Bombus, Bembex, &c., an infinity of
branching ones, like those before described in Coleoptera,
corrugate the apical margin. In the Vespidcs the uppa-
wings are folded longitudinally into three nearly equal
portions, but in the under ones the Anal Area only forms
the fold.

In the Diptera Order, as to their position when at rest,
the win<TS are mostly incumbent one on the other; but m
PsvcJwda they are deflexed, so as to form a kind of pent-
house With regard to their plicatio7i, in some, Tipula
oleracea, &c., a slight oblique semifold runs from the

. See above, p. 625. Mbid p. 635. 637,

EXTERNAL ANATOMY OF INSECTS. 641

Stigma to the apical margin, and the Anal Area has two, as it
has in many Muscidcc, itself forming nearly u right angle
with the rest of the wing; besides these it is corrugated
with minute transverse seni ifolds, which are observable also
in several other Dipterous insects ; in many Stratyomida
they are oblique, and run from the disk to the posterior
margin ; and in Asilus, Bombylius, &c., they are wavy.

5. Wearenexttosay somethingupon the ^/zop^ of wings:
this, though apparently extremely various in the different
Orders and tribes, may I think be traced in every wing
to one original prototype, a triangle with the largest angle
rounded and subtended by the anterior or costal margin:
in some, as the Coleoptera, Orthopta-a, &c., this type of
formation is a right-angled triangle- and in others, as in
iheHymenoptera, Diptera, &c., the majority of the Neuro-
ptera, &c., it is an obttisangled one"; it may be further
observed, that in receding from these forms wings very
often assume that of the half or quadrant of some regular
figure, as we shaU see when we consider those of the diffe-
i^nt Orders. Another general observation I shall firstmen-
tion,— that these organs are universally narrowest at their
base and widest at the apex, provided we consider as the

apextheterminationoutwardsofthethree Areas; otherwise
we might say that wings in the Coleoptera; Orthoptera,
&c., were wider at the base than at the apex S The win<rs
in the former Order, and in several of the Heteropterous
Hemzptera, as Gerris, Velia, &c., may in general, as to
their shape, be termed semicordate or semiovate^• in the
Dermaptera they incline to an oval figures- in the Stre^

« Plate X. Fig. 4, 5. and XXVUI. Fig. 21, 22.
l^iG. ^I, 22. d Pi.^TE X. Fig. 4. ' Ibid. Fig. S.

VOL. III.

2 T

64-2 EXTEUNAl. ANATOMY Ol- INSECTS.

^siptera, OriJioptera, most Hoinopterous and many He-
teropterous Hemiptera, they approach to the quadrant of
a circle ; in a considerable portion of the Lepidoptera the
two under wings, if united at their posterior margin, ap-
proach a circular form ; the upper ones vary a little from
the prototype of the under ones, forming an obtusangled
triangle*; in mnny Neuroptera the primary v^ings may
be called oblong or linear-oblong, while the secondar;!/
betray more evidently the right-angled or obtusangled
triangle; in the Hymenoptera this latter form is every
where conspicuous, with little deviation, except m the
rounding of the angles"; and, finally, in the /);i.^.m this
form shades off' again into an oblong, ovate, or hne^r
shape, the wing being most commonly attenuated at the
base into a kind of footstalk Some singular variations
with respect to the termination or marginal processes of
the wings are exhibited hy many Lepidoptera ; thus m
Attacus Atlas, &c., the primary wings are falcated or
hooked at their apex •>; and in great numbers both wmgs
are there scolloped into alternate bays and capes, it 1
nmy so speak, varying in depth and length e. There is
usually a sinus between every pair of nervures, each of
which terminates in the adjoining prominence, as a fold
does in the sinus K Where present, in the primary wmgs
there are eight of these sinuses, and m the secondary
where they are most usual, seven; some are remarkable
for the long tails which distinguish their secondary wmgs;
those in Papilio are usually an elongation of the fifth,from

o V T7,r fi " Ibid. Fig. 8-11.

> Plate X. i'lG.b. „ -

. , r, lo ir. Plate XIV. riG.*-

' n ; \r \ ' In Gastropacha qucrci^olw, &c.,

.J :f tI:^;.W Lepidoptera, th.e sinn^s^x.t. in the upper
^vincr>7^ and in the lower rmc. but without the folds.

EXTERNAL ANATOMY OF INSECTS. 64-3

the anterior margin, of the prominences before mentioned,
into a spathula-shaped diverging process, varying in
length and width*: but in P. Ulysses it does not diverge ;
and in P. Podalirius it is linear. They are found also in
other subgenera; thus in Uraiiia Patroclus there are two;
in U. Riphaiis three; in Erycina Cupido Jive; and in
E. Endymion six of these tails; in some, as in E.Dorylas,
the whole wing seemb to form the tail.; in others again, as
in Hesperia Proteiis and Bombyx Luna, it is an elongation
of the anal angle. Other wings in this Order are divided
into lobes resembling feathers, as you may see in Ptero-
phorus hexadactylus, &c. ^

6. We are next to consider the cMz«_^ of wings: these,
in the Orders in which they are covered by elytra, teg-
mina, or hemelytra^ are generally naked, except that the
spots in those o^Fulgora laternaria, serrata, &c., and the
whole wing in Plata, Aleyrodes, and others, are covered
with a kind of farinaceous powder; but in all theremain-
mg Orders, hairs or scales are more or less implanted in
these organs: as the Lepidoptera are the most remarkable
for the clothing of their wings, I shall leave them till
the last, and begin with the Neuroptera, If you lightly
pass your finger over the wing of any dragon-fly {Lihel-
lula F., jEshna F.), from the apex towards the base, you
will find that the longitudinal nervures are, as it were,
serrulated with very mmute bristles, which point towards
the extremity; if you next move the finger across the
wmg, from the posterior to the anterior margin, a simi-
lar circumstance will strike you. M. Chabrier conjec-
tures that, amongst other usesS these hairs may contri-

" Plate XIV. F,G. 1. Mbid. Fi<..,3.
' tor some uses of hairs, see above, p. .399—,

2 T 2

64't EXTERNAL ANATOMY OF INSECTS.

bute to fix the atmospheric fluid when the wings are
depressed in flight, while it gUdes over them as they
rise^ xnAscalaphus, Myrmeleom Nnnoptera, Hemer-o-
bius, &c., the nervures are more visibly bristled ; the
bristles diverging on each side from the longitudinal ones,
but all pointing towards the apex from the connecting or
transverse ones; in Panorpa, besides these bristles, short
hairs, pointing the same way, are thickly planted m the
membrane of the wing ; and in Hemerobius the margms
of the wing are fringed ; in the Ephemerina, CorydaUs,
&c., the wings are naked. In the Trichoptcra Order, as
their name imports, they are covered with mmute decum-
bent hairs, less easily seen but still existing m the^ se-
condary pair. In the Hymenoptera in general the wmgs
are covered with minute hairs or bristles ; but m Tiphia,
Mm-with the exception of S. Radula and affinities in
which they are hairy-and others, the wings are nearly
naked; \n Pompilus, Pepsi the hairs are infinite-
ly numerous and very short; in t\.e Sphecidce, Mutdla,
&c , they are more distinct, longer, and less numerous;
in the humble-bee {Bomhus) and many others the apex
of the wing is darkened by a large number of more con-
spicuous hairs, each of which seems to spring from a mi-
nute tubercle : as these tubercles are in a part of the wing
that is strengthened by few nervures, they may probably
be intended to supply their place, in giving firmness and
tension to this part. The wings of Diptera, under the
present head, may be viewed with regard to the hairs
that are implanted in the membrane of the wmg, m its
nermre^, and in its margin. In the first view, in Stra-

a Analyse, 24. He seems to thi..k that certain crooked hairs, in
some wings, supply the place of folds. Ilnd.

EXTERNAL ANATOMY OF INSECTS. 645

ti/omis and immediate affinities the wing is nearly naked;
but in Xylophagus, Beris, and the great majority of the Oy-^
der, the membrane of the wings is thickly planted with in-
numerable very minute bristles, not to be seen but under
a powerful lens, often black, and seemingly crowning a
little prominence, and giving the wing an appearance of
the finest net-work. As to the clothing of the nervures,
the costal, in Anthrax, Bombylius, Sec, is often remark-
ably bristly at the base, with hairs intermixed; in (Estrus
Ovis, in the inner margin or edge of this nervure, is a
smgle series of bristles, or rather short spines, like so
many black points ; in CE. Equi the whole costa is co-
vered with short decumbent hairs or bristles; in Musca
pagana F., just at the apex of the costal areolet, that ner-
vure is armed with a spur or diverging bristle larger
than the rest, which is also to be fount! in many others
of the Muscidce, some of which have two and others more
of these spurs. The little moth-like midges {Psychoda
Latr., Hirtcea F.) at first appear to have the whole sur-
face of their wings covered with hairs ; but upon a closer
examination it will be seen that they are planted in the
nerxoires, from each of which they diverge, so as under
a lens to give it a very elegant appearance ^ This fly
has its wmgs beautifully fringed with fine hairs, the
third circumstance to be attended to under this head; in
the Tipulidans, and many others of this Order, the apex
and posterior margin are also finely fringed with short
hairs. Some Dipterous insects make a near approach
to the Lepidoptera in the covering of their wings : in the
common gnat, when the wings are not rubbed, the ner-
vures are adorned by a double series of scales^ and the

» Plate X. Fig. 13.

64)6 EXTERNAL ANATOMY OF INSF.CTS.

marginal li inge also consists of tlieni=' ; and in a Georgian
genus, which appears in some degree to connect Culex
with Anthrax &c., there are scales scattered upon the
membrane as well as upon the nervures; besides, its an-
tennae " and abdomen are also covered with them.

The Order, the clothing of whose organs of flight
excites the admiration of the most incurious beholder, is
that to which the excursive butterfly belongs, the Lepi-
doptera. The gorgeous wings of these universal favour-
ites, as well as those of the hawk-moths and moths, owe
all their beauty, not to the substance of which they are
composed, but to an infinite number of little plumes or
scales so thickly planted in their upper and under sur-
face, as in the great majority entirely to conceal that
substance. Wliether these are really most analogous to
plumes or scales has been thought doubtful. De Geer
is inclbed to think, from their terminating at their
lower end in little quills and other circumstances, that
they re&ewMe feathers as much as scales Reaumur on
the contrary suspects that they come nearer to scales
Their substance, approaching to membrane, seems to
make further for the former opinion, and their shape and
the indentations that often occur in their extremity, Or-
nish an additional argument for the latter. Their num-
bers are infinite ; Leeuwenhoek found more than 400,000
on the wings of the silk- worm moth (to/Z^/-^ Mon)-
and in those of some of the larger moths and butterflies
the number must greatly exceed this. You will observe

. Reaum. iv. t. xxxix. / 4-11. ;A pomon of the an-

tenna of the insect here mentioned is figured Platk X K t ig.
' De Geer i. 63-. " R^^-^"™"

* Hoole's Leeuwenhoek. i. 63—.

EXTERNAL ANATOMY OF INSECTS* 647

however that in many Lepidopter a the wings are partialis/,
and in some instances genei-alh/, transparent : thus in
Hesperia Proteus^ a butterfly before noticed for the long
tail that distinguishes its secondary wings, there are many
transparent spots ; in Attacus Atlas, one of the largest
of moths, and its affinities, there is as it were a windo'w
in each wing formed by a transparent triangular space ;
in A. Polyphemus, Paphia, &c., the pupil of the ocellus is
transparent, which in the former is divided by a ner-
vure. In several of the Heliconian butterflies, and in
ZygtEna F., &c., the greater part of both wings is trans-
parent, with scales only upon their nervures, round their
margin, or forming certain bands or spots upon them ;
in Parnassius Apollo, Mnemosyne, Sec, the scales are so
arranged as not wholly to cover the wings, which renders
them semidiaphanous; and in some {Nudaria) the wings
are intirely denuded. With regard to size, the scales vary
often considerably hi different tribes; in Heliconia they
appear to be more minute than in the rest ; and in Cas-
tnia they are the largest and coarsest; the extremity of the
wings of Lepidopterous insects in general is fringed with
longer scales than their surfaces, and even those of the last
in the same wing sometimes vary in magnitude. The little
seeming tooth that projects from the middle of the pos-
terior margin in the upper wings of Notodonta, a subgenus
of Bomhyx L., is merely produced by some longer di-
verging hairs. The shape and fgure also of scales are
very various— some being long and slender ; others short
and broad ; some nearly round ; others oval, ovate, or
oblong; others spathulate; others panduriform or para-
bolical ; some again almost square or rhomboidal ; many
triangular ; some representing an isosceles triangle, and

(iiS EXTERNAL ANATOMY OF INSECTS.

Others an equilateral one; lastly, some are lanceolate and
others linear; again, some have a very short pedicle and
others a very long one : with regard to their extremity;
some are intire, without projecting points or incisions,
while others are furnished with them : of these some ter-
minate in a single long mucro, others have several shorter
ones ; some are armed with teeth, varying in number
from two to thirteen in different species \ Many other
forms might be enumerated, but these are sufficient to
give you a general notion of the infinite variety of this
part of the works of the Creator. I must next say a
word or two upon their arrangement on the wing. In
most instances this is in transverse lines, which some-
times vary a litde from a rectilinear course, and the ex-
tremity of the scales of one row reposes on the base of
those of the succeeding one, so that in this respect their
arrangement is like that of tiles in a roof: in some cases
it is not so regular: thus the minute scales on the
wings of Parnassius Apollo, and others with subdiapha-
nous wings, are arranged without order; in Pieris and
other Diurnal Lepidoptera, and many of the Crepuscu-
lar and Nocturnal, there appears to be a double layer of
scales on both sides of the wing ; the under layer usually
consisting of white ones. If you denude the wings of any
butterfly, which you may easily do by scraping it lightly
on both sides with a penknife, you will be amused to
trace the lines in which the scales were planted, consist-
ing of innumerable minute dots: the lines of the under
side, in some cases, so cut those of the upper side, as by

' DeGeerhas given M figures of different sailes(i. /■ iii./. 28); and
in Plate XXII. Fic 6. a-w. 22 others, collected from Reaumur,
are given.

KXTEUNAL ANATOMY OF INSECTS. 649

their intersection to form lozenges. With regard to the
position of the scales on the wing, they usually lie flat,
but sometimes their extremity is incurved : in the beau-
tiful Argynnis Vanillce a very singular appearance of nu-
merous transverse ridges is produced by the extremity
of those scales that cover the longitudinal nervures of
the primary wings, except at the base, being recurved.

But though the general clothing of the wings of Le-
pidopto-a consists of these little scales, yet in some cases
they are either replaced by hairs or mixed with them.
Thus, in the c/mr parts of the wings of Heliconian s, Ai-
taci^ Sic, short inconspicuous hairs are planted ; in a
large number of the Orders the uppej- side of the Anal
Area of the secondary wings is hairy; in several Crepus-
c\i\B,Ys{Sphi7ix Phoenix^ &c.), where there is a double layer
as before mentioned, the upper one consists of dense
hairs, except at the apex, and the lower one of scales ;
and in most of them the scales of the primary wings are
piliform, and the secondary are covered by what ap-
proach very near to real hairs ; many of the Attaci are
similarly circumstanced: the four wings oi A.Cytherea
are also covered externally with hair.

7. Before I conclude this long diatribe on the organs of
flight of insects, I must not omit some notice of the infi-
nite diversity of colours with which their wings are often
variegated and adorned by the Creator, who loves to
delight us by the beauty, as well as to astonish and awe
us by the immensity and grandeur of his works. Though
the wings in every Order exhibit instances of brilliant
and beautiful colouring, yet those of die Lepidoptera in
this respect infinitely excel them all, and to these, under
this head, after noticing a few in the less privileged Or-

650 EXTERNAL ANATOMY OF INSECTS.

ders, my observations will be confined. Although in the
Coleoptera the wings are seldom distinguished by their
splendour; yet those of some Cetoniada, as Cetonia
africana, are extremely brilliant, and resemble those of
many Xi/locopa in the lovely violet hue that adorns them:
amongst the Orthoptera some Pteroph/Uce, and in the
Homopterous Hemiptera some Fidgorce, emulate theLe-
pidoptera in the ocelli that give a kind of life to these
organs^; and a vast number of the destructive tribe of
locusts {Locusta Leach) are remarkable for the fine
colours and gaiety of their wings ^ in the Neuroptera nu-
merous Lihellulince emulate the Heliconian butterflies by
their maculation ; and in the genus Ascalaphus, which
represents the Lepidoptera by its clubbed antennae % many
also have the resemblance increased by the paintmg of
their wings, so that some Entomologists have actually
considered some of them as belonging to that Order i;
the wings of the Xi/locopcs, before alluded to, sometimes
add to the deep tints of the violet-which also prevail in
the wings of several Diptera-towavds their extremity
the most briUiant metallic green or copper varying,

" As the site varies in the gazer's hand,"
and even those wings that consist of clear colourless
membrane are often rendered extremely beautitul from the
reflection of the prismatic colours. I should undertake an
endless task did I attempt to specify all the modes ol mark-
incT, clouding, and spotting, that variegate a wmg, and all
the shades of colour that paint it, amongst the Lepidopte-
. StoU SarUerelk-s d Sabre. Pterophylla occUata f i^ii., Cigales, Frd-
^ . Bid. Sauler.de Passage, Ma Dtu-t. 1^5. L.caun^^^^^^^^
f. l6. L.cmtata <.ix. b. /. 30. &c. &c. « Plate XXV. Pig. 30.
Scopoli, Hubner.

ICXTERNAL ANATOMY OF INSECTS.

651

reus tribes; I shall therefore confine myself to a few of the,
principal, especially those that distinguish particular tribes,
and families. Of whole coloured wings — I know none that;
dazzle the eye of the beholder so much as the upper sur-
face of those of Morpho Menelaus and Telemachcs: Linn4,
justly observes that there is scarcely any thing in nature,
that for brightness and splendour can be paralleled with
this colour; it is a kind of rich ultramarine that vies with,
the deepest and purest azure of the sky ; and what must
cause a striking contrast in flight, the prone surface of
the wings is as dull and dark as the supijie is brilliant,
so that one can conceive this animal to appear like a
planet in full I'adiance, and under eclipse, as its. wings
open and shut in the blaze of a tropical sun : another
butterfly, Papilio Ulysses^ by its radiating cerulean disk,
surrounded on every side by a margin intensely black,
gives the idea of light first emerging from primeval ob-
scurity; it was probably this idea of light shining in dark-
ness that induced Linne to give it the name of the wisest
of the Greeks in a dark and barbarous age. I know no
insect upon which the sight rests with such untired plea-
sure, as upon the lovely butterfly that bears the name of
the unhappy Trojan king (P. Priamus); the contrast of
the rich green and black of the velvet of its wings with
each other, and with the orange of its abdomen, is beyond
expression regal and magnificent. But peculiar beauties
of colour sometimes distinguish whole tribes as well as
individuals. What can be more lovely than tliat tribe
of litde buttei-flies that flit around us every where in
our summer rambles, which are called blues, find which
exhibit die various tints of the sky? Lyccena Adonis of
tiiis tribe scarcely yields to any exotic butterfly in the

652

EXTERNAL ANATOMY Ol" INSECTS.

celestial purity of its azure wings: our native coppers also,
Lyccena dispar^, Virgaurece, &c., are remarkable for
the fulgid colour of these organs; in Argynnis the upper
side of their wings is tawny, spotted with black, while the
under side of the secondary ones is very often adorned by
the appearance o{ silver s^ois. How this remarkable effect
of metallic lustre, so often reflected by spots in the wings
of butterflies, is produced, seems not to have occupied
the attention of Entomologists. M. Audebert is of opi-
nion that the similar lustre of the plumes of the hunmiing
birds {Trochilus) is owing to their density, to the pohsh
of their surface, and to the great number of little minute
concave mirrors which are observable on their little
beards''. But these observations will not apply to the
scales of the wings of butterflies, which are always very
thin and generally very flat: in some instances, as in
3Iorpho Menelaus, there appears more than one very slight
channel upon a scale; but this takes place also in others
that reflect no lustre. Their metallic hues must there-
fore principally be occasioned by the high polish of their
surface and the richness of their tints. It is the purity
of the white, in conjunction with their shinmg surface,
contrasted with the dull opaque colour of the under side
of the secondary wings, that causes the spots that decorate
those of the Fritillaries {Argynnis) to emulate the lustre
of silver. In Papilio the Trojans are distinguished by
the black wings with sanguine spots, and the Greeks by
the same with yellow spots ; but these have proved in
some instances only sexual distinctions ^ In the Danai
candidi L. the colour of the tribe may be described as

=> Plate III. Fig. 1. ^ N. Did. d'Hist. Nat. viii. 257-

' See above, p. 303.

EXTERNAL A.VATOMY OF INSECTS. 6'53

sacred to the day, since every shade, from white or the
palest yellow to full orange, is exhibited by them. The
yellows prevail also in those Noctiue, the trivial names of
which Linne niade to end in ago, as N. Fulvago, Citrago,
&c. I must not conclude this part of my subject with-
out noticing one of the most striking ornaments of the
wings of LepidojHera, the many-coloured eyes which de-
corate so large a number of them. Some few birds, as
the Peacock and Argus Pheasant, have been decked by
their Creator very conspicuously with this almost
dazzling glory; but in the insects just named it meets us
every where. Some, as one of our most beautiful but-
terflies, Vanessa Io\ have them both on the primary and
secondary wings; others, as Noctua Btibo^ only on the
primary; others again, tis Smerinthus ocellata^ only on
the secondary: m some also they are on both sides of the
wing, as in Hipparchia Mgeria^, and in others only on
the upper side, as m Vanessa lo ; in others again only on
the under side, as in Morplio Teiicer^: in some likewise
they are very large, as in the secondary wings of the same
buttei-fly: and in others very small, as in those in the
wings of the blues {Lyccena). Once more, in some they
consist only of iris and ptipil, as in Hipparchia Semele,
and in others of many concentric circles besides, as in
Morplio Teucer, &c.

v. Legs ^ We are next to consider those organs of
motion affixed to the trunk, by which insects transport
themselves from one place to another on the earth or in

* Sepp. I. i. t. vii./. 6. b Rcemer Genera t. xxii. f, 2

" ^^epp. r. m. i. n. / 7. 1 Ibid. i. t. vi. /. 7

' Rcemer ubi snpr. t. xiv. /. 1 . < Plates f; r, rff

65't EXTERNAL ANATOMY OF INSECTS.

the water, and by which also they perform various ope-
rations connected with their economy In treating of
them we should consider their number; kind; substance-,
articulation with the trunk; position; proportions; cloth-
.ing; composition; folding; and motions.

1. Number. Having before very fully explained to you
the number and kind of the legs of insects in their pre-
paratory states'^, I shall now confine myself to the con-
sideration of these organs in their perfect or last state ;
beginning with their number. Insects, properly so call-
ed, as L formerly observed S in this state, including the
anterior pair or arms, have only six legs, none exceeding
or faUing short of this number ; but in several of the
Diurnal Lepidoptera {Vanessa, &c.) the anterior pair
are spurious, or at least not used as legs, the tarsi having
neither joints nor claws ^; this in some cases is said to be
only a sexual distinction <=. In Onitis, Fhancsus, and some
other ScarabdeidcelA^l.., the arm has either none or a spu-
rious tarsus or mamis^; which in the first of these genera
is also a sexual character. From both these instances
we see that walking is only a secondaiy use of fore-
legs in the insect tribes. Besides insects proper, a whole
tribe of mites [Caris Latr., Leptus Latr., Astoma Latr.,
Ocypetc Leach) have only six legs; the rest, and the
Arachnida in general, have eight; in the Myriapods,
Polly xenus has twelve pairs; Scutigera has ff teen; the
terrestrial Glomerides {G. Armadillo, &c.) sixteen; and
the oceanic (G. ovdlis) twenty; the oriental Scolopendra
Leach, twenty-one; Polydesmus has usually about thirty

- See above, p. 546- . " Ibid. 131—

c Vol II p 307. De Geer 1. 5CX. /. 11.

c Reg^^e AM iii. 546. ^ Plate XXVII. F.c 44. 4.^.

EXTERNAL ANATOMY OF INSECTS.

665

pairs: Craspedosoma, Jfty: Geophikis electricus at least
sixty; in Mus terrestris there are more than seventy; in
/. sabulosus nearly one hundred; in I.fusais, 124>; and in
/. maximus 1 34 pairs or 268 single legs. But with respect
to the Geophili, Mi, &c., it is to be observed, that the
number of pairs varies in different individuals; and the
circumstance that has been before mentioned'', that these
animals keep acquiring legs in their progress to the per-
fect state, instead of losing them, renders it difficult to
ascertain what is the natural number of pairs in any
species.

2. Ki?ids. Upon a former occasion I gave you a suffi-
ciently full account of the kinds of legs % and I have also
assigned my reasons for giving a different denomina-
tion to the anterior legs under certain circumstances''; I
shall not therefore enlarge further upon this head.

3. Substance. The substance of the legs is generally
regulated more or less by that of the rest of the body,
only in soft-bodied insects they seem usually more firrii
and unbending. Each joint is a tube, including the mov-
ing muscles, nerves, and air vessels.

4. Articidation with the Ti-unh M. Cuvier has ob-
served that the hip {cQxa\ which is the joint that unites
the leg with the body, rather inosculates, in its acetabu-
lum, than articulates in any precise manners* but this
observation, though true of a great many, will not apply
universally, for the legs of Orthopterom insects, and of
most of the subsequent Orders, are suspended rather than
inosculating. Even in many Coleoptera a difference is ob-
servable in this respect. I have before mentioned that

" Vol. II. p. 312, 363. 365. ^ See above, p. 546—.

' Anatom. Compar. i. 453.

656 EXTERNAL ANATOMY OF INSECTS.

what are called the p^wc/a ordinaria, which distinguish the
sides of the prothorax of many Scarabreida and Geotru-
pidce, form a base for an elevation of the interior surface
with which the - extremity of the base of the clavicle,
which plunges deep into the breast, ginglymates ^ ; this
structure may also be found in other Lamellicorns, as
the stag-beetle (Lucanus) and Dynastes^ that have not
those excavations ; in these last it is an elevated ridge
forming a segment of a circle with, it should seem, a pos-
terior channel, receiving a corresponding cavity and pro-
tuberance of the clavicle. With regard to the mid-leg,
in Copris, the coxa is emboxed in a nearly longitudinal
cavity of the medipectus. and the coxa of the hind-leg an-
teriorly is suspended to a transverse cavity of the post-
pectus, but posteriorly it is received by a cavity of the
first segment of the abdomen ; so that it may be regard-
ed as suspended anteriorly, and inosculating posteriorly.

In some tribes of this Order, as the Weevils {Curculio
L.) and Capricorns {Ceramhyx\ the coxae of the four an-
terior legs are subglobose'' and extremely lubricous, and
are received each by a socket that fits it, and is equally
lubricous. In the bottom of this externally, and in the
head of the coxa, is an orifice for the transmission of
muscles, nerves, and bronchiae; but the coxa is sus-
pended by ligament in the socket. This structure ap-
proaches as near the ball and socket as the nature of the
insect skeleton will permit; the high polish of the arti-
culations acts the part of synovia, and the motion is in
some degree rotatory or versatile, whereas in Copris, &c.,
lately mentioned, it seems to be more limited, and is pro-

» See above, p. 308.

" Plate XXVIl. Fig. 18, 19.

EXTERNAL ANATOMY OF INSECTS. 657

bably, at least in the mid- and hind-legs, only in two di-
rections; in the middle pair, probably, from the coxa
being in a position parallel with the breast, opposite to
that of the hind pair. In Dytiscus L., Carabus L., and
some other beedes, die coxa?, especially die posterior pair,
appear to be fixed and hicapable of motion. In many
insects these coxae seem to belong as much to the abdo-
men as to the trunk. We have just seen this to be the
case in Cojn-is, &c.; and in the Lepidoptera, if the former
be separated from the latter, the legs will be detached
with it.

4. Location. We are now to consider the location and
position of the legs, both in general and with respect to
each other. And first, as has been before stated, we may
observe diat, in the hexapods with wings, the arms belong
to the manitrimk, and are attached to the antepectus on
each side the prosternuni; and the two pair of legs to
the aliti-^mk, the mid-legs being attached to the viedipec-
ins, between the scajndaria and mesosternum ; and the
hind-legs to the postpectus, between the parapleura and
the postermmi; and further, that the arms are opposed
to the prothorax: the mid-legs to the mesothorax and the
primary organs of flight; and die hind-legs to the me-
tathorax and ihe secondarxj organs of flight; though in ■
some cases the wings appear to be behind the legs and
in others befm-e them : thus, in Panorpa, the former are
nearer die head than die latter; but in the Libelbdina the
reverse of this takes place, the legs being much nearer
the head than the" wings : in both cases, however, the
scapidaria and parapleurce run from the legs to die
wings, but in an oblique direction; and mPanorpa these
pieces assume the appearance of articulations of the legs.

VOL. III. 2 u

658 EXTERNAL ANATOMY OK INSECTS.

In most of the apterous hexapods they appear to be
attached laterally between the thorax and the pectus^;
but in the flea {Pulex) they are ventral In this tribe the
arms are usually stated to be inserted in the head^'. but
I once succeeded in separating the head of a flea from the
trunk, and these organs remained attached to the latter
As to the Octopods and Arachnids, in the mites (Acajics'L.)
they are lateral, and in their analogues, the spiders
{Ara7iea L.), they emerge between the thorax and the
breast, which last they nearly surround ; in the Phalan-
gidce the bases of the coxae approach near to each other,
being separated only by a narrow sternum; in their an-
tagonists, Chelifer and Scorpio, they apply to each other,
the anterior ones acting as maxillce. In the myriapods
the legs of the Chilopoda Latr., and some Chilognatha,
as Glomeris, are inserted laterally, a single pair ui a seg-
ment ; but in lulus L. their attachment is ventral, the
coxae seem to spring from a common base, and there are
two pair to each segment^ except the three first, which
bear each a single pair.

I shall next consider how the legs are located with re-
spect to each other. To render this clear to you I shall
represent each of the variations, which amount in all to

Mr Montague describes the legs of Ntfctenbia, as dorsal {Linn.
Trans, xi. 13) ; but Dr. Leach calls them lateral (Samouelle, 303).

" N. Diet. d'Hist. Nat. xxviii. 247. " Plate XXIH. 1^ ig. 4.

<i Plate XXVII. Fig. 58. M. Savigny affirms that these msects
cannot have, and really have not, but one pair to each segment ; only
that the segments are alternately membranous and shelly, and that
the former are concealed under the latter {Anim. sans Vertebr. 1. 1.44.):
but, pace tanti viri, I cannot discover that any suture separates these
portions from each other : so that, admitting his theory, they must
be regarded as two segments soldered together.

EXTERNAL ANATOMY OF INSECTS. 659

twelve in the hexapods that have fallen under my notice,
by six dots.

1. In this arrangement the legs are all planted
near to each other, there being little or no interval be-
tween the pairs, and between the legs of each pair. It
is exemplified in the Lepidoptera, Blatta, and many
Diptera.

2. Similar to the preceding, but the anterior pair
are distant from the two posterior; exemplified in the
hee.H{A2ns) and most Hymenoptera ; Chironomus: Scu-
tdlera; Pachysoma K.*

3. :: Like the last, but the posterior pair is distant
from the two anterior. Examples : Silpha, Necrophorus,
Telephorus, he.

^. Similar to the last, but the legs of the posterior
pan- are more distant from each other than the four an-
terior. Ex. Curcnlio L.

5. The legs of each pair near each other, but the
pairs distant. Ex. Gibbium.

6. : :• Both the legs of each pair and the pairs distant.
Ex. Blaps, he.

7. .... Anterior pair distant from the two posterior
and the legs of the middle pair rather more distant
from each other than those of the other pairs. Ex. Sea-
rabceiis M'=L.

; . Like the preceding, only the legs of the mid-
dle pan- are at a much greater distance fi-om each other.
Ex. Coprh M<=L.

9. : : Legs of the two posterior pairs distant. Ex.
Hister, Scaphidium.

It is by this arrangement of the legs that Pachysoma is princi-
pally distinguished, as a subgenus, from Scnrahceus M' L.

2 u 2

660 EXTERNAL ANATOMY OF INSECTS.

10 Like the preceding, but the posterior legs

more' distant than those of the middle pair. Ex. Lygceus.

11. ; Like the last, but the legs of the anterior
pair also distant. Ex. Velia.

12 .• The arms distant, intermediate legs more di-
stant* posterior legs close together. Ex. Byrrhus L.

5 Proportions. In general the legs of some insects
are disproportionally long and slender, as in Phalan-
ghm Opilio and some species of Gonyleptes^: those
of others are disproportionally short, as in Elater, &c.
With reo-ard to their relative proportions, the most ge-
neral ruL is, in Hexapods, that the anterior pair shall
be the shortest and most slender, and the posterior the
lonoest and thickest; but there are many exceptions:
thus, in Macropus longimanus, Clytra Imgmana &c., m
the male the arms are the longest ; again, a thing that
very rarely occurs, in the same sex oi Podalirius retusa
J intermediate legs are the longest- but in Bluna bar-
Urostris and many weevils they are the shortest: m Sa-
perda hirtipes 01iv.'= the hind4cgs are disproportionally
fono-: with regard ^o thicJcness, they are in general extijme-
ly sknder in Cicindela, and in the Scaral^.^d. very t^^ck^
In Goliathus Cacicus the arms are more robust d. an the
four legs ^ ; in Gyrhms the latter are more dda ted han the
fler^ in man'y m^elid., and particularly m d.e ce^e
brated Kanguroo beede i^Scarahcercs Macropus Fianc.) the
hind-legs are much the thickest ; in a new genus of wee-
V Is from Brazil i^Plcctropr. K.), the intermediate pair aie
^ove slender than either the arms or the posterior pair

3 See above, p. 37. 2. «./. 18. ii. 296—

Oliv. Tns.Ga. t. i /. 8.

EXTERNAL ANATOMY OF INSECTS. 661

6. Clothing. The hairs on the legs of insects, though
at first sight they may seem unimportant, in many cases
are of great use to them, both in their ordinary avocations
and motions : but as most of these were sufficiently no
ticed when I treated of the sexes of insects S I shall not
here repeat my observations, but confine myself to cases
not then adverted to. Some insects have all their legs very
hairy, as many spiders, the diamond beetle {Entimus im-
perialis), or at least a species very near it and common
in Brazil", &c.: in otliers they are nearly naked, as in
the stag-beetle. In the Crepuscular Lepidopie7-a (Sphinx
L.) and some of the Nocturnal ones {Bombi/x L.) the
thighs are much more haiiy than the rest of the legs :
and in Luccmus, Geotrupes, and many other Lamellicorns,
&c., the anterior ones have a yellow or golden spot at
their base, composed of decumbent hairs, which prevent
them from suffering by the violent friction to which they
are exposed in burrowing. In most Petalocerous beetles
the tibiae are set with scattered bristles, and sometimes
the thighs. The Tiger beetles {Cicindela) are similarly
circumstanced: but the bristles, which are white, are ge-
nerally arranged in rows. InDytiscus, Hydrophilus, &c.,
the four posterior tarsi; and in Notonecta the posterior
pair, and also the tibiae— are fringed on each side with a
dense series of hairs, which structure assists them in
swimmmg<=. The tarsi, especially the anterior pair, in a
certain family Lamia F. {L. papulosa. Sec"), are simi-
larly fi-inged, only the hairs curl inwards ; and the hand

' See above, p 305-. b This variety appears to clifFer

very httle from the Curculio imperials of Fabricius and Olivier ex-
cept in the remarkable hairiness of its legs. Vol II n 563

" Oliv. Ins. n. 67. t. xx. f. 15G. " "

662 EXTERNAL ANATOMY or INSECTS.

in Sphex and AmmophUa, but not in Peloj^aus and Chlo-
rion^ is fringed externally with long bristles.

7. Composition. With regard to their composition,
both arms and legs generally consist offve pieces, which
Entomologists have denominated— the coxa or kip— the
trochanter — the femur or thigh— the tibia or shank— and
the tarsus or foot. Where the structure and use of the
fore-leg is different from that of the four hind-legs, I pro-
pose calling these pieces by names corresponding with
those which anatomists have appropriated to the arm in
the higher vertebrate animals : thus, as you will see in
the table, 1 call the whole fore-leg the hrachiuvi or arm ;
and the coxa becomes the clavicula or collar-bone ; the
trochanter, the 5mp/Z« or shoulder-blade ; the femur, the
humerus or shoulder; the tibia, the cubitus or arm; the
tarsus, the ma^ius or hand. But let me not lead you to
suppose that the pieces, either in the arms or legs of in-
sects, which are there named after certain others in verte-
brate animals, precisely correspond with them— by no
means— since that is a very doubtful point; and some of
them, as the trochanter, clearly do not. Many gendemen
skiUed in anatomy, as I have before observed % have
thought that what is regai'ded as the coxa in insects really
represents the femur: but there are considerable difficul-
ties in the way of this supposition, several of which I then
stated. I shall not however enter further into the sub-
ject, and take the above names; since this application of
them is so general and so well understood, except with

^ See above p. 591. Some physiologists have been of opinion,
that in l»rds, what is called the thigh should properly be denominated
the Libm, and that this last is really the tarsus. Illiger, Tt-rmmohgw,
184. § 185. n. ^,'16.

EXTERNAL ANATOMY OF INSECTS. 663

regard to the fore-leg, under certain circumstances, as I
find tiiem. I shall now consider them in the order in
which I have named them.

a. Coxa or Clavicula ^. The coxa is the joint that
connects the leg with the trunk of the insect. With re-
gard to their shape^ the most general form of the four
anterior is more or less that of a truncated cone : in the
Staphylinidce, however, they tend to a pyramidal or four-
sided figure; as do the whole six in the Trichopta-a: in
numbers of the weevils and capricorns they are subglo-
bose ; in the Lamellicorns they are mostly oblong, and
not prominent: the posterior pair in the Coleoptera are
generally flat and placed in a transverse position, and more
or less oblong and quadrangular : in Elater, &c., they are
cuneiform : in Haliplus Latr. they are dilated, and cover
the thigh ^ : in Btiprestis, Copt-is, &c., they have a cavity
that partly receives it : the corresponding part, the cla-
vicle, in the arm of Gryllotalpa, is very large and re-
markable; viewed underneath it is triangular, and trifid
where the trochanter articulates with it : in that of Me-
gachile Willughbiella the clavicle is armed with a spine <=.
As to their propoi'tions, the most general law seems to be,
that the interior pair shall be the shortest and smallest, and
the posterior the longest and largest. In some instances,
as in Buprestis, the two anterior pair are nearly equal ;
in others {Mantis, Eurhinus K.), the anterior are the
longest, m the former as long as the thigh, and the four
posterior the shortest : in the Trichoinera, Lepidoptera,
&c., all are nearly equal ; in Mantis the two posterior,
and mPhengodes the intermediate pair are the largest; but

" Plates XIV. XV. XXVII.;,. " Plate XV. Fig. ]. p",
■■ Plate XXVII. Fig. 27.

664;

EXTERNAL ANATOMY OF INSECTS.

in Nccro})horus tliey are the smallest : — though almost
universally without articulations, in Galeodes the clavicle
consists of two and the coxa oi' three^.

h. Trochanter or Scapula ^. This is the second joint
of the leg: and if the coxa is regarded as the analogue of
the thigh in vertebrate animals, this should seem to re-
present the jpatella or rotula^ vulgarly called the knee-
pan. Latreille and Dr. Virey consider this articula-
tion as merely a jouit of the coxa'=-; but if closely exa-
mined, especially in Coleopterous insects, you will find
it so fixed to the thigh as scarcely to have separate mo-
tion from it, and in many cases it seems to be merely its
fulcrum; but I am not aware that any instance occurs m
which it has not motion separate from that of the former
joint.

As to its articulation with the coxa, — ^in the Cole-
optera it appears to be of a mixed kind ; for it inoscu-
lates in that joint, is suspended by Hgament to its ori-
fice, and its protuberances are received by correspond-
ing cavities in it ; and its cavities receive protuberances,

• T T,

which belongs to a ginglymous articulation. 1 have
observed two variations in this Order, in one of which
the motion of the thigh and trochanter is only in tiw di-
rections, and in the other it is nearly versatile or rotato-
ry. The Laviellicorns afford an example of the first, and
the Bhyncophorous beetles or weevils of the second. If
you extract from the coxa the thigh with the trochanter
of the larger species of Dynastes M^L., you will find that
the head of the latter is divided into two obtuse incurv-

» L Dufour, Dcscr. dcs six Arachn. &c, : Annates Generates, &c.
1820. 19. L Ixix./. 7. d. " Plate XIV. XV. XXVII. </'.

iV. Diet. d'Hist. Nat. xvi. V.)o. xxvi. 157.

EXTERNAL ANATOMY OF INSECTS.

665

iiig lobes or condyles ; that on the inner side being the
smallest and shortest, and constricted just below its apex;
and that under this is a shallow or glenoid cavity, ter-
minating posteriorly in a lubricous flat curvilinear ridge.
If you next examine the trochanter in articulation with
the coxa, you will perceive that the head of the former
inosculates in it, that the lower condyle is received by a
sinus of the coxa, which also has a lubricous vei-y shallow
cavity corresponding with the ridge, in which it turns ;
and in the head of the coxa, on the lower side, is an ex-
ternal condyle, which is received by a sinus common to
both, of the head of the thigh and of the exterior side of
the trochanters in which it likewise turns: this last con-
dyle has also an internal protuberance, which appears to
ginglymate with a cavity of the trochantei- : from this
structure the leg is limited chiefly to a motion up and
down upon two pivots, or to fold and extend itself. You
will find an articulation very near this, but on a smaller
scale, in the stag-beetle. In the other kind of articula-
tion, which admits of freer motion, the head of the tro-
chanter is prolonged, and the process terminates in a
short interior condyle, which appears to work in a cor-
responding cavity of the interior of the coxa; and the
base of the process is encompassed by a ridge with a
cavity behind it, which is received by another of the
lower part of that piece, and admits a corresponding
ridge— a structure that allows a rotatory motion. In the
hind-legs of this tribe the motion is chiefly limited to
folding and extending; in Carabiis, &c., also the head of
the trochanter is nearly hemispherical, and the articula-

" Platk XXVn. Fig. 12. b.

666 EXTERNAL ANATOMY OF INSECTS.

tion approaches ball and socket. In most of the other
Orders, the Hymenoptera excepted, there is little or no
inosculation, the trochanter being simply suspended by
ligament to the coxa as well as to the thigh: its connec-
tion with the latter is similar in Coleoptera; but in Ct-
cindela, &c., it inosculates in it. The part we are con-
sidering varies in its position with respect to the thigh :
in the hind-legs of Carahus, &c., it forms a lateral ful-
crum on the inner side of that part, and does not inter-
vene between its base and the coxa; the muscles from
the latter entering the former, not at the bottom of the
base, but at its side : but in the four anterior legs it
forms their base, as it does in all the legs m Apion, and
in all the Orders except the Coleoptera, cutting them en-
tirely offfrom contact with the coxa: in the Lamellicorns
they cut off part of the base obliquely, but so as to per-
mit their coming in contact with the condyle of the coxa,
as before mentioned. In the IchneumonicUE and some
other Hymenoptera the trochanter appears to consist of
joints particularly visible in the posterior legs^
As to size in general,-the part in question is smaller
than the coxa; but in ^otonecta it is larger, and m tlie
dog-tick [Ixodes Ricinus) longer than that jomt. It ex-
hibits few variations in its shape or appendages worthy
of particular notice. In general, in the Coleoptera it is
triangular or trigonal; but in Carahus L., in the hind-
leg it is oblong or rather kidney-shaped; in that of A^e-
crophonis^ it terminates in one or two teeth or spines,
varying in length in the different species : in the other
Orders it is not remarkable in this respect.

Plate XXVII. Fig. 20. q

^ Ibid. Fig. 28.

EXTERNAL ANATOMY OF INSECTS. 667

c. Femur or Humerus The femur or thigh is the
third, and usually the largest and most conspicuous joint
of the leg. In the hypothesis before alluded to'' it is
considered as the analogue of the tibia of vertebrate
animals. With regard to the articulation of this part
with the trochanter, it has been sufficiently explained
under that head, and that with the tibia I shall treat of
when I come to that joint. As to the size of the thighs,
and their relative pr-opwtions to each other and to the
remaining joints of the leg, the most general law is, that
the anterior pair shall be the shortest and smallest, and
the posterior the longest and largest. With respect to the
remainingarticulations, most commonly the z;Az;g7ns longer
and larger than the tibia, and the tibia than the tarsus.
But there are numerous exceptions to both tliese rules.
With respect to thefrst, we may begin by observing that
the increase of the magnitude of the thigh, from the an-
terior to the posterior pair, is usually gradual : but in
many jumping insects, and likewise many that do not
jump, the posterior pan- are suddenly and dispropor-
tionally thicker than the rest Again, in many insects
the anterior pair are the longest and thickest, as in Ma-
cropus longimanus, Bibio, Nabis, Sec: in others, the in-
ierjnediate exceed the rest in magnitude, as in 07iitis
Aygidus, cupreus ; Sicusjavipes, &c. ; in many Lamelli-
corns all the thighs are incrassated and nearly equal in
size: but in some, as Ri/ssonotus nebtdosus M''L.<^, the
intermediate pair are rather smaller than the rest. With
respect to the seco?id rule — in some, as in the male of
Macropus lojigimanus, the anterior tibia, though more

PLATJi XIV. XV. XXVII. •> Sec above, p. 591. 662.

'■ P- 314—. Linn. Tram. xii. xxi./. 12.

668 EXTERNAL ANATOMY OF INSECTS.

slender, is longer than the thigh in Hololepia maxil-
losa it is longer and more dilated ; in Lamia marmorata,
or one related to it from Brazil, the intermediate, pair are
longer; in Ateuchus gihbus and others of that tribe the
posterior thighs ate smaller than the tihia: and, to men-
tion no more ; in Callichroma latipes the posterior tibia
is wider than the part last named. Again, the tarsi are
as long as either tibia or thigh in many of the larger Dj/-
7iastidcE, as Megasoma Actcson, &c. ; longer than either
in Melolontha suhspinosa F. ; and in Tiphia^ Scolia and
affinities, often as long, or longer than both together.

As to shape, — the thigh, especially in the fore-leg, varies
considerably : most generally it is flat, linear, and a little
thicker where it is united to the tibia, on the outer
side convex, and concave next the body ; but in many it
is gradually thicker from the base to the apex : in some
Ceramh/ces (C. thoracicus) it is clavate; in others of this
genus and Molorchus they may be called capitate ; in
Pterostichus they are rather lanceolate ; in Onitis Sphi^ix
the humerus is triangular, and the intermediate thigh
rhomboidal ; in Bruchus Bactris it is bent like a bow ;
and in some Brazilian Halticce it is nearly semicircular.
The humerus in Phasma is attenuated at the base ; m
Empusa gongyloides it is at first ovato-lanceolate, and ter-
minates below in a kind of footstalk ^ ; m Phasma fa-
helliforme it is dolabriform " ; in Mantis often semioval
or semielliptical, and thickest at the inner edge, which
affords space for two rows of spines with which it is
planted. In Phyllium siccifolium all the thighs are fur-
nished on both sides with a foliaceous appendage nearly

' StoU Spectres f. xvi. /. 58, 59.

Ibid, i.xyiii. /. 65.

EXTERNAL ANATOMY OF INSECTS.

669

from base to apex* : in a species of Empusa {E. maa^o-
ptera\ the four posterior ones are so distinguished only
on their posterior side ^ : others of this last genus, as
E. gongyloides, have an alary appendage on both sides
at the apex of these thighs ; and another family, as
E. pauperata, have only one on the posterior side ^. The
thighs of no insect are more remarkable for their elegant
shape, — tapering gradually from the base to the apex,
where they swell again into a kind of knee, — than the pos-
terior ones of the locusts {Locusta Leach) ; each side of
tliese thighs is strengthened with three longitudinal nearly
parallel ridges, and the upper and under sides are adorn-
ed by a double series, in some coalescing as they ap-
proach the tibia, of oblique quadrangular elevations re-
sembling scales ^.

I shall next say a few words upon the spines and other
p-ocesses which arm the thigh. Those moveable ones of
Mantis which help to form a fearful instrument of de-
struction, have just been mentioned, and similar ones, but
less conspicuous, arm the intermediate thighs Siaisjla-
vipes : other appendages of this kind are for a less de-
structive purpose — to keep the tibia when folded in its
place. This seems to be the use of the serratures and
spine that arm the thigh of Bruchus Bactris, or the
HymenoYiterous genera. Leucospis, Chalcis, Sec; in 0?iilis
Aygidus a short filiform horn arms the humerus, and a
longer crooked one that of many species of Scaurns In
many Stenocori the thighs terminate in two spines, and

" Stoll Spectres t. vii./, 25. " Ibid. t. viii./. 30.

" Ibid, zcbi siipr. " Ibid. t. x. / 40.

Platk XIV. Fig. 5. This appearance of scales on the thighs h
principally confined to this tribe. ^ Plati; XXVII. Fig. 23.

670 EXTERNAL ANATOMY OF INSECTS^

in Gonyleptes K. the posterior ones are armed internally
with very strong ones; with which, as the legs converge
at their kneeS they may probably detain their prey. The
knee-pan {Gonytheca) of the thigh, or the cavity at its
end, which receives the head of the tibia, is very conspi-
cuous in the weevils ; but in no insects more than in
Locusta \ in which tribe it deserves your particular at-
tention.

d. Tibia or Cubitus^. The tibia or shank is the fourth
joint of the leg, which according to the hypothesis lately
alluded to is the analogue, in the anterior leg of the car-
pus or carpal bones, and 'mt\ve four piosterior ones of the
tarsus or tarsal bones of vertebrate animals. This may
be called the most conspicuous of the articulations of the
leo-; for though it is generally more slender and often
shorter than the thigh, it falls more under the eye of the
observer, that joint being more or less concealed by the
body: it consists in general of a single joint; but in
the Araneidce and Phalangidce it has an accessory one,
often incrassated at its base, which I have named the
Epicnemis

With respect to the articulation of the tibia with the
thigh— we may observe that in general it is by means of
three processes or condyles, two lateral and one interme-
diate, of the head of the former joint ^: the lateral ones
are usually received by a cavity or sinus of the gonytheca

. Linn. Trans, xii. . xxii./. 16 ^.//^V^Xvif"
and XXVII. Fig. 15. r". Plates XIV XV. XXVIl. s .

d Plate XXVII. Fig. 21. s". M. Savigny (Amm. smis Vcrtcbr. I.
i 46 Note h.) seems to think that this structure obtains in all his
iriropods; viz. the Octopod Aptera, Arachnida, and Mrjnapoda: but
it seems to me evident only in the two tribes mentioned in the text.

" Plate XXVII. Fig. 6, 16, 17. (" -

EXTERNAL ANATOMY OF INSECTS. 671

of the thigh ^ ; and upon these the tibia turns, with a
semirotatory motion up and down as upon a pau- of pivots:
at the same time the mola or head of the latter joint,
which has often a flexure so as to form an elbow with the
rest of it, inosculates in the gonytheca, and is also sus-
pended by ligament to the orifice through which the
muscles, nerves, and bronchias are transmitted: so that
m fact the articulation, strictly speaking, belongs exclu-
sively to none of the kinds observable in vertebrate ani-
mals, but partakes of several, and may properly be de-
nominated a^mixed articulation,— a term applicable in nu-
merous instances also to the other articulations of the legs
of insects. In the different Orders some variations in this
respect take place,— I will notice some of the most re-
markable. In no Coleopterous insects is the structure
more distinctly visible than m the larger LameUicorns.
In Copris bucephalus, for instance, if you divide the thigh
longitudinally, you will find on each side, at the head,
that it is furnished with a nearly hemispherical protube-
rance, perforated in the centre for the transmission of
muscles, and surrounded externally by a ridge, leaving a
semicircular cavity between them " : if you next examine
the tibia, after having extracted it, you will find on each
side, at the base, a cavity corresponding with the protu-
berance of the thigh which it receives, having likewise a
central orifice, and surrounded by a semicircular ridge
corresponding with the cavity in the thigh in which it
acts : below this ridge another cavity, forming a small
segment of a circle, receives the ridge of the thighs You
will observe that the ridge of the tibia represents the

" P^:^^f;XXVII. F,o. 15. b Ibid. Fig. 11. r'".

Jbicl. Fig. 10. /

672 EXTERNAL ANATOMY OF INSECTS.

lateral condyle lately noticed : in the Dynastidce this is
more prominent, and often forms a smaller segment of a
circle. In these also the protuberance of the thigh is
more minute, and its ridge is received by a cavity of the
tibia nearly semicircular in Geotnipes Latr. the articu-
lation is not very different, though on a reduced scale ; m
Calandra Palmaruvi the lateral condyles of the tibia are
flatter and broader ^ and the articulation not being quite
so complex, this joint is kept steady by an intermediate
process observable in the gonytheca". From the above
description it appears that the dislocation of the tibia is
effectually prevented in the Lamellicorns by the protube-
rance and ridge of the thigh working n their correspond-
ing cavities, while the condyle of that part turns with a
rotatory motion in the cavity of the thigh. In the Or-
thoptera Order tlie tibia is suspended by a ligament, in
the gonytheca the lateral condyles, which are very pro-
minent, working in a sinus of that part''. The subse-
quent Orders exhibit no very striking variations from
these types of articulation, I shall therefore not detain
you longer upon this head.

With regard to the p'oportions and magnitude of the
joint we aie considering,— the most general law is, that
the anterior pair should be shorter and more slender than
the intermediate; and the intermediate than the posterior
and that all the tibia; should be shorter and more slender

^ Plate XXVII. Fig. 8. Thigh, a. Protuberance, b. Semicircular
cavity, c. Ridge. Fig. 9. Tibia, a. Central cavity, b. Ridge, c. Exte-
rior cavity. ' Ibid. Fig. 6. a. Ibid. Fig. 7- a.

Ibid. Fig. 15. Thigh Locusta Leach, a. Sinus m which the con-
dyle of the tibia works. Fig. 16. Tibia of Do. aa. Lateral condyles,
b. Intermediate one.

EXTERNAL ANATOMY OF INSECTS. 673

than the thighs, and longer and thicker than the tarsi.
Various exceptions, however, to this rule in all these cases
might be produced ; but I shall only observe that in all
those insects in which the fore-legs are calculated for dig-
ging or seizing their prey, as in the Petalocerous beetles,
the Gryllotalpa, Mantis, &c., this joint of the leg is
usually much enlarged and more conspicuous than the
others.

As to ks Jigure and shape — most commonly the tibia
grows thicker from the base to the apex, as in the majority
of Coleoptera, Hymenoptera, &c.; in the Orthoptera, Neu-
ropta-a, &c., it is generally equally thick every where.
Another peculiarity relating to this head observable in
it, is its tendency to a trigonal figure : this, however,
though very general, is not universal ;- thus, in some
Orthoptera, as Ptey-ophylla K., its horizontal section is
quadrangular ; in others, as Locusta Leach and many
other insects, it is nearly a circle ; in some scorpions it
is almost a hexagon. The superficial shape also of this
joint in numerous instances is more or less triangu-
lar, but it sometimes recedes from this form :— thus, in
Callichroma latipes it is a segment of a circle ; in some
Empides it is clavate; in Onitis Sphinx, dolabriform ; in
the Orthoptera, Neicroptera, &c., it is usually linear ; in
some Lygai it is angular^: but the most remarkable
tibice in this respect are those of such species of this last
genus as have the posterior ones winged or foliaceous,
so that they resemble the leaf of some plant— the tibia
being the rachis, and the mng (which in some species
is veined) representing the leaf itse\L This structure is

" Stoll Punnixcs, 1. \.f. 67. /. xvi./. 114.
VOL. III. 2 X

674 EXTERNAL ANATOMY OF INSECTS.

exemplified in Lygc^us compressipes, phi/Uopns, foUaceus,
&c/ Under this head 1 must say a few words upon
thefexure of this joint, which in some cases merits no-
■ tice. I have before mentioned its bend at the knee'' or
base : the apex also is sometimes incurved— in the ante-
rior one of the male omacropus longimanus so as almost
to form a hook- in Lygaus Pharaonis the posterior pair
are flexuosed; \nBruc1ius Bactris, Leucospis, and several
species of Chalets, these tibice curve so as to adapt them-
selves to the bend of the thigh when folded. The notch
on the inside of the anterior pair, in a large majority ot
Carabus L., armed above by a spur % a structure which
probably assists them in seizing and detainmg their prey,
may also here be introduced : in the generality it is a lit-
tle removed from the apex of the joint in question; but
in Pamborus it is very near to it, and in Cychrus, Cara-
bus, &c., it becomes obsolete. I may mention here also
a singular character which distinguishes the cubit of both
sexes of Gryllus campestris, domesticus, &c. At the base
there is an aperture which passes through the jomt-an-
teriorly it is oval, and posteriorly elliptical and much
larger, and on both sides is closed by atense membrane
The most striking pecuharities as to the clolhng ot
his joint have been chiefly noticed under the sexual cha-
racters of insects S but some appear not to be of that de-
scription. In Sph^ridncm Leach, while the thighs and
tarsi are naked, the posterior tibice are remarkably beset

. StoU Punaises, i. n. f. H. . viu. / 54 ^.f.^-
c ^ See above, p. o / 1.

■^^•S-''""; Rfi t iii f 12. Compare ScarabcB,ts longmanus,
c Ohv. Ins. n 6G. t. in. ./. ^ 1^^^^^ ^^^^^^.^^^^ ^ 20.

lUd. n. 3. t. IV./. 2/. , g 306 -.

• Plate XXVIl. 1<ig.31.

EXTERNAL ANATOMY OF INSECTS. 675

witli Stiff bristles ; in Empis pennipes they are thickly
fringed on both sides; in Scarabceiis M«=L. only exter-
nally, and in Di/tiscus serricor7iis internally ; in Neajdalis
harpipes K. this fringe is longer at the apex ; and in Sa-
perda hirfipes Ol. the same tibia at that part are adorned
with a large brush, like that observable in the antennae
of some Lainice^.

I must next call your attention to the teeth, spines, and
spurs with which the tibice of insect? are sometimes armed.
With regard to teeth, you have doubtless often observec}
those that distinguish the cubitus of the arm of most La-
melhcorn beetles : these vary in number from one, as ii)i
Trox suberosiis, to seve7i, as in Geotrupes autumnalis; but
the most universal number is three : in some species of
Geotrupes, as G. stercorarius, &c., the third tooth from
the apex, and those that follow it, may be called double.
These teeth, in their cubit or anterior shank, doubtless
assist these insects in burrowing. The four posterior
tibicB in this tribe are also distinguished by a kind of teeth
which occupy their whole diameter, and resemble so
many steps. I have before noticed the remarkable cubit
of the Gryllotalpa, and likewise that of Semites, Pasi-
machus, &c., in which some of the teeth are prolonged
into spines ^ which are the next description of tibial arms
that I mentioned. Spines are of two kinds—those whick
are mzxdy processes of the crust of the//Z>m, and those that
are implanted in it, and seem to have a gomphosis or per-
liaps an amphi arthrosis articulation An instance of the
Jirst kind may be seen in the hind-legs of some grasshop-

» Oliv. Ins. XX. G8. t. i. / 8. comp. n. 67. i. xii. /. 83. and Platk
XII. Fig. 25. a. «. Vol. JI. p. .365. and Pr.AXE XV. Fig. 5. G.

' See above, p. 433, Note b. and 404, Note a.

2 X 2

G76 EXTERNAL ANATOMY OF INSECTS.

pers^ (Lofwste Leach), the Rutelid^, &c. though mothers
they are implanted :— of the second, in the cubitus of the
Maniidce, and of «// the ^/i/^ of the dragon-flies [Lihelhdina
M'^L.) and o^both kinds in the hind-legs oiJcridaK.t
those which arm the upper angles of the tibiae being ;jro-
cesses, and those of the lower being implanted. The term
spine I think ought to be restricted to the first kind; the
second ought rather to be denominated simrs {calcaria),
and may perhaps be regarded as in some degree synony-
mous with those most important appendages of the jomt
in question, that are implanted in or near their apex,
which have been hitherto distinguished by this last deno-
mination, and which I am next to consider. But though
I have not altered a term generally adopted, I must here
expressmy opinion that they oughtrather to be considered
as minute toes or fngers, and that the denomination best
acrreeing with their functions, as accessories to the main
toe, would be digituU: this is proved particularly by a
character peculiar to those of many species of the genus
Cimbea: amongst the saw-flies, in which these organs are
furnished with a sucker or pulvillus (as they are also in
(Enas a kind of blister beetle), as well as the joints of the
^arsi - which makes it evident that they are applied by
' the animal to surfaces, and assist it in walking or climb-
ing; and in general it may be observed that in most in-
sects their principal nse is connected with these motions,
and with burrowing. This circumstance tends to prove
VTV Vrr ^ " I* remarkable that in this

See above, vol. n. p. 331.

EXTERNAL ANATOMY OF INSECTS.

677

that the generality of insects (for all have not these
organs) have really a didactyle or tridactyle hand or
foot; and the hypothesis so often alluded to— that the
cubitus or tibia, &c., is really analogous to the carpus or
tarsus in vertebrate animals ^ — seems to receive nO small
confirmation from it; since, if the sjpursh^ really ana-
logous to Jingers or toes, the part they articul ate with
cannot be the tibia, &c. Though the parts in ques-
tion did not escape the notice of Reaumur, Linne, De
Geer, Latreille, &c., yet they have not been employed
in the determination of tribes, genera, &c., except by the
author last named, but perhaps adopted from Bonelli'',
m the subgenera Zabrus and Pelorus : in many instances,
however, they afford excellent subsidiary characters,
sometimes common to a whole Order, and at others di-
stinguishing its various subdivisions. With regard to
their number — I have noticed many variations which I will
now state to you, first observing that I shall express them
by three figures, the^rst representing the number of spurs
on the anterior leg, the second that of those on the inter-
mediate, and the third on the posterior ; and where there
are spurs, as in the Trichoptei-a and Lepidoptera, on the
middle as well as at the end of the tibia, I shall express it
by one figure over another, the upper one representing the
number of the middle spurs. If you make an examina-
tion yourself, it will be proper to remind you that these
little organs are extremely liable to be broken off, but the
socket in which they were planted is usually very visible.
The most natural number is represented by 2:2:2; this

* See above, p. 591, (567, &c. ^ Rcgnc Animal, iii. 191. I have
never Iiad an oppoi tnnity to consult Bonelli's 0/jscrv. Eniomolog.
the genus Carabus L. in tlie Memoirs of tiie Tui-in Academy.

678 EXTERNAL ANATOMY OF INSECTS.

you will find very prevalent in the Coleoptera Order,
lis in the Predaceous and numerous other beetles : in
the Orlhoptera and Hemiptera Orders, however, I have
not discovered an instance of it ; but in all the rest it
more or less occurs : next to this wwrnh^x— tibia with
obsolete or no spurs seem most prevalent, particularly m
the Hemiptera; not a single instance of an insect fur-
nished with them occurring to me in the Heteropterous
section ; and it is doubtful whether there are any in the
Ho7nopterous.—H^\mg stated the most universal struc-
ture in this respect, I will next consider the Orders se-
riatim. Amongst the Coleoptera though the numbers
2:2:2 are most frequent in occurrence, yet there are
numerous exceptions. Thus, in the Lamellicorns, 1:1:1
represents the calcariao^ one tribe of the Smraid?zWieM'^L.
formed of the genus Scarahceus M^L. ; 1:2:1 represents
those of anotlier tribe of that family, including the sub-
genera Ateuchus, Copris, Phanceus, &c.; 1:2:2 again
forms the character in this respect of Aphodius and the
great majority of the Lamellicorns; while 2:2:2 is con-
fined in this section to jEsalus F. and Melolontha chri/so-
meloides Schranck {Psephus M<=L. MS.). In the other
tribes of Coleoptera other numbers occur. Thus, 0:1:1
characterizes Hyloecetus; 0:1:2 Mordelki; 0:2:2 Ma-
cropus; i:2:2 Harpalus, and all those Cam^'^' L., ex-
cept Zabrus, that have a notch in their anterior tibicc ;
^: 2:2 Zabrus. In the Orthoptera Order it is not etisy
to distinguish the real spurs from the implanted spines
that frequently arm the legs : these in Blatta are ex-
tremely numerous, even at the apex of the tibia ; but I
cannot distinguish any that can be regarded as true ana-
logues of the former : the most natural number of spurs

EXTERNAL ANATOMY OP INSECTS. 679

in tliis Order is represented by 0:0:4; this you will see
in all tlie Locusts; in Acrida, Conocephala, Pterophylla;
and in T7-uxalis, Pneimora, &c.; in Phasma there are
none. In Mantis, if the terminal process of the cubitus
is excluded, it will be 0:2:2; in Gryllotalpa, admitting
the terminal teeth of that part^ as analogues of spurs,
the number is 4:4':4f; in Tridacti/lus Latr. 0:0:5'' ; m
Gi-yllus Latr. 3:3:5; in Gryllus monstrosus, 4:4:6. In
the whole Hemiptera Order I have discovered no instance
of an insect furnished with the real spurs : for though in
Tettigonia F., Cercopis, &c., there are implanted spines in
the posterior tibia, and several at the apex, there are none
of them clearly analogous to real spurs. In the Lepido-
ptera the most general arrangement appears to be -^-: 2:-|.;
and next to this, ^:2:2. In this Order most commonly
there is no spur at the end of the cubit, but one resem-
bling a thumb arms its middle; in Pier is, &c., this
thumb is not present, so that the number is 0:2:2: in
Agarista heach, Erebus, &c., you will find -i-: 2: 4, the
posterior calcaria being all terminal; and in Attaais
Atlas, all these organs are obsolete except the thumb.
In the Neuropta-a the most general arrangement is
2:2:2; hxitin ih^. Libellulina, although the legs are very
spinose, there are no spurs. In the Trichopiera K., in
Pkryganea rhombica and affinities, the number of them
is expressed by i:i:-t; and in those with long antenna?,
P. atra, &c., by I" the HymenojUcra the number

1:2:2 is most prevalent ; and next to this, as in Apis L.,
1:1:2. In the Ichmmones minuti L. the spurs are

» Plate XV. Fig. 6. v" . Coquebert lUustr. Jc. iii.

1. XXI. f. 3. D. " Plate XXVIl. Fio. 29, v".

680

EXTERNAL ANATOMY 01" INSECTS.

1:1:1; in AUa Latreille, a kind of ant*, 1:0:0. In the
Diptera it is often difficult to distinguish the spurs from
the spines ; but the number most universal is, I think,
2:2:2; in Tipula it is 1:2:2; in the Tabmiidce 0:2:0;
and in Culea; Limonia, &c., there are none. Amongst
the insects with more than six legs, most commonly the
tibiae have no spurs ; but in the Araneidce each is armed
with too, a circumstance which also distinguishes the
corresponding joint of the j^^dipalpi.

These little organs inosculate each in an appropriate
socket of the end, or in many cases of the middle of the
iibia; and that part of their head or base that is received
by it, is often constricted for the purpose : from hence
it follows that they are capable of some degree of motion,
but in some insects, as those on the four posterior legs of
Scarabceiis sacer and its more immediate affinities, and
those at the end of the cubit of Gryllotalpa^ they are im-
moveable, and appear almost processes of the joint to
which they belong. They are commonly sharp, of a
subtriquetrous figure, with the lower side flat: where
there are two, the outer one is usually the longest ; and
in general the spurs on the hind legs are longer than
those on the four anterior : but there are exceptions —
thus, in Acantliapus Latr. the intermediate spurs are the
longest; and in Cicindela the anterior are longer than
the former ; in Blaps morti&aga those on all the legs are
nearly equal in length. They vary sometimes m shape —
those on the middle of the cubit of many Lepidoptcra^

« Most of Latreille's genera of ants arc confirmed by differences
in their spurs. Thus Formica is 1 : 1 : 1 ; Vonera 1:2:2 with the
internal intermediate one pectinated: Myrmica 1:2:2 with all syn>
nietrical, &c.

EXTKKNAL ANATOMY OF INSECTS.

6'81

which may be regarded as a kind of thumb ^, ai-e of a
lanceolate shape ; in Meloe the external posterior one is
flat and obtuse ; in (Enas Latr. it is obconical, concave
at the extremity, and apparently furnished with a sucker;
in Ateuchis smaragdulm the anterior ^ and in Coprh Ca-
rolina the -posterior is forked and emarginate; in Sir ex the
former is hooked and winged ; in Lamprima it is trian-
gular and dilated ; in Aphodius analis it is dolabriform ;
in Di/nastes retusus and Juvencus the spurs are bent like
a bow. In many Hi/rnenoptera, as the Sp/iccidce, they are
jjectinated'', with a series of minute parallel spines— a
structure which assists the animal in burrowing <=; in
Acanthopus Latr. they are armed with little teeth or
spines'*; in the hive bee the spur of the cubit is furnished
with a membranous appendage which I have called the
velum"; and in a subgenus related to Saropoda Latr.
{Ctenoplectra K. MS.), the interior spur of the posterior
leg is crescent-shaped, fixed transversely, and fitted on
the inner side with a membrane, the edge of which is
finally pectinated.

e. Tarsus or Manus ^ This is the last portion of the
leg, usually supposed to be analogous to the hand or
foot of vertebrate animals ; but, according to the hypo-
thesis so often alluded to, rather the representative of
their jointed finger or toe. In treating of this part I
shall consider its articulation with the tibia^ and of its
joints inter se.- the number of those joints; their propor-
tion and shape; their parts and appendages.

Platk XXVII. Fig. 29. v". ^ Ibid. Fig. 33. v'".
" Linn. Trans, iv. 200. Note«. " Plate XXVII. Fjg 32 v'"
' Ibid. Fig. 36. a-.

f Plates XIV. XV. XXVI. XXVII. «", t".

682 EXTERNAL ANATOMY OF INSECTS.

I seem to have observed three kinds of tarsal articula-
iion. The Jrst is a species of enarthrosis or ball and socket,
the joints terminating in a globular head, perforated in-
deed for the transmission of muscles, &c., and which is
received by a corresponding cavity of the tibia or pre-
ceding joint, as may be seen in many weevils [Ciirculio
L.^). This admits of some rotatory motion. — The second
is a mixed articulation between enarthrosis and gingly-
mus, when at the base of die ball a deep transverse
channel receives a corresponding ridge of the tibia or
preceding joint : this may be found in Riitela and pro-
bably many other Lamellicorn beetles; and something
very similar in the Predaceous ones.— The third kind is
Avhere there is litde or no inosculation, and the joints are
scarcely more than suspended: this takes place in the
Orthoptera, Neuroptera, &c.; but mBlatta and the hind
legs of Mantis there is some approach to the foregoing
kinds.

We are now to consider the number of joints of the
tarsus, which varies considerably in the different Orders,
and in one has been assumed as a clue for a subdivision
of it into sections^ which, though not perfecdy natural,
is very convenient, and has been adopted by most modern
Entomologists. In treating of this head, I shall use
those denominations that have been employed by M.La-
treille and others to express the variations of the num-
ber of the tarsal joints in the Colcoptcra, but shall apply
them to insects in general. Insects in this view, there-
fore, may be c2Sie<^ pcntamerous ; hetcromerous ; tetra-
merons; trimerous; dimerous; or monomerous.

« Plate XXVI. Fig. 44, 46, 4/. a.
0 By Gtoffvoy— Hist. Lis. i. 58.

EXTERMAL ANATOMY OE JNSECTS.

683

Penlameroiis insects are those which have five joints in
all their tarsi. This is the most universal, and. may be
called the natural number of these joints. More than half
the Coleoptera belong to this section ; in the Orthojitera
— the Blaitidce, Mantidce, and Phasmidce ; all the Lepi-
doptera except those butterflies called teirapi ( Vanessa^
&c.); all the Trichoptera^ Hymenoptera^ and Dipiera;
in the Neuroptera — Ascalaphus, Myrmclcon^ Heinerohinsy
Corydalis, &c. ; and in the Aptera — Pulcx^.

Hetei-omermis insects are those in which the number
of these joints varies in the different paii's of legs''. These
variations, like the spurs, may be expressed by three
figures, the first representing the anterior tarsus, the
second the intermediate, and the third the posterior. I
begin with 5:5:4'. This number represents those beetles
that have been exclusively regarded as heteromerous by
modern Entomologists — of this description is tlie Lin-
nean Tenehrio, Meloe, &c., now subdivided into nume-
rous genera ; they have Jive joints in the two anterior
pair, and four in the posterior. The tarsal joints of the
aquatic genus Hydroporus (a singular anomaly in the
Order to which they belong) are expressed by 4:4:5,

* The CleridcE, which M. Latrcille has placed in the pentamcroits
section, vary considerably in the number of their tarsal joints. Tlius
in general in Thanasimus the tarsi axe peiitamerom ; but in T.for-
micarim they appear to be heteromerous ; and in Enojyliuvi, Opilo,
Clerus and Necrobia they are tetrameroits. M. Latreille's expression,
[N. Diet. d'Hist. Nat. vii. 172.) " Ic premier article etant fort court et
cache sous la second," seems to indicate that there is a Ji/l/i joint in
some of these, the first being concealed under the second ; but I have
never been able to discover it. Perhaps he reckoned the 2^ulvillus as
a joint?

The term heleromcrous properly belongs to aU insects in which
the different pairs of tarsi vary inter se in the number of their joints,
and it is here used in that liyge sense.

G84

EXTERNAL ANATOMV OE INSECTS.

thus reversing the number in the preceding tribe : other
Heteromerous genera are to be found amongst the He-
miptera. Thus, in Jianatra the numbers are 2. 1. 1.; in
Sigara and Nauceris 1 : 2: 2; in a new subgenus between
Belostoma and Naucoris {Xiphostoma K. MS.), brought
by Dr. Bigsby from Canada, 3:2:2: in the Lepidoptera
the butterflies called tetrapi {Vanessa, &c.) may be ex-
pressed by 1:5: 5. Amongst the Aptera and Arachnida
there are three remarkable genera, which if their pedi-
palps are included may be deemed Heteromerous. I
mean Fhrynus, Thelyphena, and Galeodes;— in the for-
mer the numbers will be *: 4: 4: 4, the asterisk denoting
more than ten; in the second, 8:4:4:4.; and m Gale-
odes) in which the first pair of pedipalps are not chelate,
the mandibles performing their office) the numbers are
1:1:3:3:3.*

Tetramei'ous insects are those in which all the tarsi
consist oifour joints ; these in the Coleoptei-a are next in
number to the pentameroiis—mdeedi a very large propor-
tion of them strictly speaking are really of the latter
description, since in Linne's four great genera, Curculio,
Ceramhyx, Chrysomela, and Cassida and some others,
the claw-joint {ungida) consists of two articulations, one
very short, forming merely the ball at its base^^j which
inosculates in the socket of the preceding joint, and the
other constituting the remainder : if you carefully sepa-
rate these two pieces, you will find that the last inoscu-

» These three genera appear really to have only six \eg% since the
pedipalps or maxillary legs are not armed with claws, while the
real representatives of the legs, or three last pair, are so distm-
guished. In Phrynus and Thchjphona the anterior pair are chelate ;
but in Galeodes they are pediform, as in the Arancidct, and the great
chete are the mandibles. " Plate XXVI. Fm. 47, 48. d *.

EXTERNAL ANATOMY OF INSECTS.

685

lates in the summit of the ball, and is moved by appro-
priate muscles =*. This structure probably permits the
readier elevation and depression of this joint. In the
Orthoptera the tetramerous genera are those which
Linne called Tettigonia amongst his Grylli [Locusta F.);
Acheta monstrosa also, and in the Neuroptera, Raphidia
belong to this section.

Trimermis insects are Uiose whose tarsi consist of only
three joints. Amongst beetles the Lady-birds {Cocci-
nella L.) are remarkable for this structure, but in tliem
the claw-joint is also bi articulate, so that strictly speak-
ing they are tetramerous ; in the Orthopterous Order the
migratory locusts [Loaista Leach) belong to this sec-
tion, as likewise Giyllns Latr. and Gryllotalpa Latr. :
in the first of these genera is an appearance of there be-
ing more joints in the tarsus, because there is more than
one cushion below the first''. To this section also belong
the great majority of the Hemiptera, excluding only those
tribes that connect the two sections of the Order consti-
tuting the two Linnean genera Nepa and Notonecta ; the
Libellulina likewise belong here, as do also the Scor-
pionida; and Scolopendridce.

Dimerous insects are those that have two joints in
all their tarsi. Such are the Pselaphida; in the Co-
leoptera Order *=; in the Hemiptera — Belostoma and No-
tonecta; in the hexapod Aptera — Pediculus; in the octo-
pod — the ^ca;7 of Linne; in the myriapod — lulus; and
in the Arachnida — the Araneidce.

» Plate XXVI. Fig. 49. a. . Vor.. TI. p. 330.

" Dr. Leach says there are three joints in this tribe. Nat. Muc.
iii. 80.

686 EXTERNAL ANATOMY OF INSECTS.

Monomerous insects are those which have only a shigle
tarsal joint. Only one Coleopterous and also one He-
mipterous genus is so distinguished : the first is Der-
mestes Armadillus DeGeer% and the second the common
water-scorpion, Nepa luSlr. Among the Aptera we
find Nirmus, Podura, Sminthurus, &c., that belong to diis
section.

To the above sections another may be added for those
insects whose tarsi have more than/w joints, which may
be denominated Polymerous. Here belong the genera
Go7iyleptes K., Phalangium and Scutigera Latr. In the
first the nmnber of joints varies from six to eleve?i, and
in the two last they far exceed that number, amounting
in some species of Phalangium to more than Jifty, and
becoming convolute like the antennae of Ichneumons ^.

I am next to notice the proportions and shape of the
tarsus and its joints. The most general law is, that it
shall be shorter and more slender than the tibia ; but it
admits of several exceptions— thus, in Megasoma K. S i»
all the legs; in Agrostiphila M'^L. MS.^ in the i?iter-
mediate, and in Amphicoma lineata in the posterior pair
the tarsi are the longest; in Trichius Delta these last
are longer than the thigh and tibia together. In some
insects the tarsi axe disproportionally short, as in Cas-
■sida, the Pselaphida, Locusta Leach, &c. Though ge-
inerally more slender than the tibia, in several instances

a From De Geer's description this insect seems related to Agafln-
dium (iv. 221— t. viii./. 31" 23). M. Leclerck de Laval discovered
it to be monomerous. Regne Animal, ni. 365.

b Plate XXVII. Fig. 22. See above, P; 31 1- Note a.

.1 Melohmtha sericea and aurulenla. Lhw. Trans, xn. 463. 400. be-
long to this subgenus.

EXTERNAL ANATOMY OF INSECTS. 687

they are as thick or thicker, or more dilated, as in most
of the tetramerous beetles, which being climbers require
a dilated tarsus. Again, comparing the three pairs of
this joint with each other, the most general rule is, that
the anterior should be the sJiortest, and the posterior the
longest: but in some, as the Capricorn beetles, &c., they
are nearly equal in length ; in others, as Lytta marginata,
the anterior pair, and in RhipipJiorus the iritei-mediate,
are tlie longest ; in TricJiiiis Delta these last are the
shortest. With respect to thickness, the anterior tarsi,
except in many males*, are not very strikingly different
from the rest.

With regard to the proportion of the jomts of the
tarms to each other, — according to the most general law,
the first is the longest, the last next in length, then the
second and third, and the fourth is the shortest. In Gony-
leptes K. and other Phalaiigidce the first is almost thrice
the length of all the rest taken together; but there are
numerous exceptions to the rule. In the female Carahi
the first joint is not longer than the last, and in the males
not so long ; and in Hydrophilus, &c., it is the shortest of
all. Again, the second joint is longer than the three fol-
lowing ones in Dasytes ater^; and than the last in Cicindela
sylvatica : the third]on\t is shorter than the fourth in Lam^
pyris ignita : it is longer than the first in Donacia, many
Melolonthida, &c. Once more, the fourth joint, usually
the shortest of all, is longer than the second and third
in Anthia, &c. Lastly, the claw-joint, usually the second
in length, in the Eprohoscidea Latr. {Hippohosca L.) is
very long and large, while the four first joints are so

See above- p. S.'JS —

" Plate XXYII. Fjg. 26,

688 EXTERNAL ANATOMY OF INSECTS.

extremely short as to be scarcely distinguishable from
each other : it is the shortest of all in Colymbetes, &c. ;
it is of the length of the third in Cicindela sylvatica^ of
fourth' m C. sexguttata. Though commonly the slen-
derest joint of all, paTticularly so in Raphiclia, in many
Heteromerous and Lamellicorn beetles it is the largest,
conspicuously so in Mellimis tricinctus. Sometimes, as
in Buprestis chrysis, &c., all the tarsal joints are nearly
equal in length and thickness.

We are next to say something upon the shape of the
tarsi and their joints. In general we may first observe
that their upper surface is commonly more or less con-
vex, and the lower flat or concave : in insects that are
swift runners, as the terrestrial Predaceous beetles, they
are usually slender and filiform^; in those that swim, as
Dytiscus, the two posterior pair taper nearly to a point
from the base to the apex"'; in some that climb, as Bu-
prestis, they are rather flat and linear; and in others (the
Weevils, Curculio L.) they grow gradually wider towards
the claw-joint <=; sometimes, as in Mordella Latr., the four
anterior tarsi are of this shape, and the posterior pair
setaceous. In Gyrinus the four posterior are flat and
triangular; and in that extraordinary insect Gryllus mon-
strosus the tarsi are foliaceous and lobed'*. In many
males and some others the anterior pair ox hands are of
a different shape from the two posterior : thus, in several
Carabi they are lanceolate; in Staphylinus, Creophilus,
&c. in both sexes they are often nearly circular, like
those of male Dytisci'. With regard to the shape of

» Plate XIV. Fig. 7- i'. " I^^'^l- F'^- 6-

' Plate XXVI. Fm. 47. " Pi ^te XXVII. Fig. 41.

' Plate XV. Fig. 9.

EXTERNAL ANATOMY OF INSECTS.

689

individual joints it may be said in general that they are
rather triangular, with an anterior sinus for the reception
of the succeeding joint: the first joint usually departs most
from this form; in the bees it is commonly much larger
than the rest, especially in the last pair of legs, and nearly
formmg a parallelogram ; in Euglossa it is trapezoidal; in
the majority nearly linear or filiform. With regard to
their termination — vaBracliycerus and some ants {Ponera,
Mymiica, &c., Latr.) the three Jirst joints \ in Dascillus,
Lyais reticnlatus and affinities, the third unA fourth; and
in tlie great majority of the Tetramerous insects the
petiultimate joint is bilobed; although in most Predaceous
beetles this jomt is entire or simply emarginate, yet in
CoUiuris it terminates in a single oblique lobe ; and in
Lebia^ Drypta, &c., it is nearly bipartite. I must now
advert to the U7igula or claw-joint : it is usually clavate
or thickest at the end and curved ; but in the AsilidtB it
is shaped hke a vase or cup ; in Phanceusy in the four
posterior tarsi, in which the claws are obsolete, it is
thickest at the base and sharpest at the extremity ''; it
usually forms an angle with the rest of the tarsus, risincr
upwards, which enables the insect to move more easily
without hindrance from the claws, and also more readily
to lay hold of any object it meets with ; but in the La-
mellicorn beetles and many other insects it is in the same
line with it. As in the beetles last mentioned this joint
is often inserted in the extremity of the preceding one;
but in CEdemera it articulates with the middle of its
upper surface; and in Lycus and a numerous host of

» Mon. Ap. Angl. i. t. xii. veut.f. 20.
Plate XXVII. Fir.. 44. s:
VOL. III. 2 Y

690 EXTERNAL ANATOMY OF INSECTS.

Tetramerous beetles it springs from its base, just behind
where it diverges into two lobes.

I shall next call your attention to the diffierent kinds
of appendages with which the tarsi are furnished. They
are seldom armed, like the tihi(E, with teeth, or spines,
or horns ; but something of the kind occasionally distin-
guishes them. In Phileurus, Oryctei,, and several other
Dynastidce, the first joint is armed at the apex externally
with a considerable mucro ; in the fore-leg of Dasytes
ater a similar process is prolonged into a crooked horn^.
But the most important appendages of the tarsi are the
clam which almost universally arm their extremity, and
which appear clearly analogous to those of birds, qua-
drupeds, &c., though probably differing as to their sub-
stance". Some few, however, are without them ; this, as
I lately observed, is the case with Plianceus with respect
to the four posterior legs ; the anterior ones of V anessa
amongst the Lepidoptera, and all those of Stylops and
many Acari L., are also without them : this is likewise
the case with the first pair of legs, or the second of the
pedipalps of Galeodes. In this genus these organs con-
sist of two joints*^. With respect to 7iumber they vary
in different tribes, but not so much as the calcaria:
these variations may likewise be represented by three
numbers. The most natural is tvoo in all the tarsi, exhi-
bited by the Predaceous beetles and the great majority ;

2.2.1. are to be found in Hoplia, Anisonyx, &c.^•

1.2.2. in Belostoma; three in all the legs in the Ara-

Plate XXVII. Fig. 26. iv" . " See above, p. 39G.

L. Dufour Descr. dc six Arachmks. Annales, &c. 1820. 19.
J Plate XXVII. Fic. 51. is the posterior claw of Hoplia.

EXTERNAL ANATOMY OF INSECTS.

691

neida^ : in Meloe^, Elatei\ &c., each claw is double or
consisting of two, which makes fou7- in each leg ; and in
ma.ny Hippohoscidce there are six"-, in Nepa and the
Myriapods there is only one. In most msects, perhaps,
the claws are simple or undivided''; but in Galmica,
Melolontliamhspinosa"^ &c., they are bifid at the apex; as
is the exterior claw of the four posterior legs in Cliamo-
<//aand Maa-aspis M'^L., and o^ all in Meloloniha lwr~
iicola; in Serica hrunnea M'=L. the claws are all cleft at
the extremity, but the internal tooth is broad, flat, and
obtuse S; in Melolontlia vulgaris and Pdidnota punctata
M'^L.^ the claws are armed with an internal tooth near
the base". In the Araneidcp^ which have three claws, the
two external ones are funnshed with several parallel
teeth, which the animal uses to keep separate the threads
of its web, and probably for other purposes'^; and some
Predaceous beetles, as Lehia and Cymindk^ have both
their claws similarly furnished These organs vary in
their relative proportions: thus, in Anoplognathus the
inner claw is much smaller than the other™; and in Elaier
sulcatus,fuscipes, &c., it is represented by a mere bristle ;
in Hoplia, in the anterior tarsus it is not half the length
of the outer one "; in Areoda and Pelidnota M<=L. this
last is the smallest. They vary also in length — in Ryn-.
cJianus^ Ascalaphus^ &c., they are very short; m the La-
melUcorns, Galeod^s, &c,, very long ; and in Myrmeleon

» Plate XXITI. Fig. 14. <- Plate XXVII. Fig. 62.

' Ibid. Fig. 46. .i Ibid. Fig. 53, 54.

' Ibid. Fig. 49. f Ibid. Fig. 38.

« Ibid. Fig. 39. " This structure is not general in this genus.

' Plate XXVII. Fig. 40. ^ Pl^te XXIII. Fig. 14

' Plate XXVII. Fig. 43. " Ibid. Fig. 47.

" Ibid. Fiq. 48.

2 Y 2

692 KXTERNAL ANATOMY OF INSECTS.

loncrer than the claw-joint. With regard to tlieir curva-
tiire they generally lorm the segment oi a circle ; m many
Asilida they are crooked like the claws of the eagle
and the posterior one of the HopUce is bent like a hook " :
they most commonly diverge from each other ; but in
the Rutelidce, Anoplognathida, &c., they are perfectly
parallel, and in the former often inflexed ^ With regard
to other appendages of the part we are treating of, if you
examine the stag-beetle and many other LameUicorns,
you will find between the claws a minute but conspicuous
joint terminated by two bristles which seem to mimic
the ungula and its claws ; these parts are what are deno-
minated in the table the palmida, plantula, and pseiidony-
chia: in the stag-beetle these are long^ in the Melolon-
ihidce short = ; and in many Cetoniadce they resemble an
.intermediate claw.

The most remarkable of the appejidages of the tarsi are
to be looked for on their under side or sole {solea\ and
are the means by which numbers of insects can overcome
atmospheric pressure and walk against gravity. Many
of these have been fully described in a former let-
ter f ; but much that relates to them was there omitted,
which I shall now detail to you. Four kinds of p2dvilli,
as I would call these appendages, are found in the sole
of insects, upon each of which I shall make a few remarks.

The Jirst is a cushion or brush composed of very thickly
set hairs or short bristles : examples of this you will find
in the majority of Tetramerous and Trimerousheet\e%. In
Ch-ysomela, Timarcha, &c., there is one of these cushions

^ Plate XXVII. Fig. 53. " Ibid- Fig. 51.

, Ibid. Fig. 47. Mbid. F lo. .^6.^./^,/*.

^ Ibid. Fig. 49. «^^,/*. ' ^'"i- P-

EXTERNAL ANATOMY OE INSECTS.

693

on each of the three first joints; in Pr tonus, Liparus,
&c., there is a pair; and in Coccifiella on the ^ttJO first; in
others {Balaninus Nucum, &c.) a pair only on the penul-
timate joint ; in Calandra Palmarum, RJiina barbirostrist
Sec, that joint has an intire cushion ; in Eurynotus mu-
ricatus K. * the three first joints of the four anterior tarsi
are similarly circumstanced, but the cushions resemble
sponge^.

The second kind of cushion is a vesicular membrane
capable of being inflated. This distinguishes the tarsi
of Thrips'^, and many Acari L.'^; likewise those of
Xenos^l and also of many Orthoptera fully described on
a former occasion ^, though the fact of their capacity of
inflation has not been ascertained, belong to this sec-
tion.

The third kind of covering of the sole is when the
three or four first joints of the tarsus each terminate in
one or tisoo membranous lobes or appendages : of the first
description is Priocera K., in which the lobes are invo-
lute ^ ; and of the second Rhipicera Latr. \ in which
there is a pair on each joint, in the Brazil species set
with very fine hairs.

The fourth and last kind are what may with the utmost
propriety be denominated suckers, since their use as such
is clearly ascertained. These are not only to be found
in a large proportion of the Diptera, in some of which
there are two of them, as in the Jsilida ^ j and in others

' Linn. Trans, xii. t. xxii. /.I. b p^^j. ^^i^^j. instances of

this structure, see above, p. 336. <^ De Geer, iii. 7,

Ibid. vii. 84. Plate XXVII. Fi g. 60, 63.
' Ibid. Fig. 61. f Vol. II. p. 327— .

^ Plate XXVII. Fig. 59. " Linn. Tra?is. xii. t. x\i. f. 3

' Plate XXVII. Fig. 53. ' '

694.

EXTERNAL ANATOMY OF iNSfiCTS.

three^ as the Talanida;^ ; but also in many of the subse-
quent Orders: thusj, in the HeteropteroUs Hewiip^CT a, in
Scutellerd and Pentatoma, but not the Reduviadce, and
in the Neuropterous genus Nymp'hes Leach there is a mi-
nute one under each claw. It is discoverable between the
claws in many Hymenoptei'a, as Apis Vespa, &c. But
the genus that exhibits to the curious Entomologist the
most singular and elaborate apparatus of this kind is
Dyi>iscus Latr. ; and the examination of the under side of
■the /zar^rZ of any waZg of this genus will almost compel the
most inattentive observer to glorify the wisdom and skill
of the Allfather so conspicuously manifested in 'the
structure of these complex organs. For this part in these,
instead of two or three pedunculate cups as in the in-
sects just mentioned, is composed of a vast number, some
iarge and some small. If you take a male specimen of
the commoli D. marginalis, you will find that the three
first joints of the hand are very much dilated, so as to
form a plate or shield nearly circular, fringed all round
with stiffish haii^s ; if you next examine the under side of
this plate with a good magnifier, you will discover at the
base, where it is united to the cubit, two circular cups,
the ^external one more than three times the size of the
bther, with ati umbilicated centre «=; besides these two
larger tups the rest of the shield is covered by a vast
number of Minute ones of a sirtiilar construction <i : the
•larger cups are nearly sessile, but the sraaUer are
elevated upon a tubular footstalk the three first joints
of the intermediate tarsi are also dilated, but not into an

Plate XXVIL Fig. 54. Philos. Tram. 1816. i. xviii./. 9—11.
b Platf. XXVII. Fig. 55. t. * Plate XV. Fig. 9. a.

I Uiid. b- ' P/'ifos. Tram. 1816. /. xx. /. P, 12-ls5.

EXTERNAL ANA'J'OMY OT INSECTS. 695

orbicular shield, and thickly set with minute peduncu-
lated suckers^. The structure varies however in dif-
ferent species. Thus in Z). Umbatus the shield is trian-
gular with the smaller suckers at the base, and two rows
of larger oblong ones, concave but not umbilicated, at the
apex ; in another Brazilian undescribed species (Z). ob"
ovattis K. MS.) the shield is oblong and quite covered
with suckers like those last mentioned; inD.sulcatus {Aci-
lius Leach) almost the whole plate is occupied by a very
large sucker, above which, at some distance in the inner
side, are two smaller ones, while the extremity of the
shield is covered by minute ones elevated on long foot-
stalks: the central umbilicated elevation of the large one,
which nearly fills its cavity, is in this species beautifully
radiated. The male of Colyinbetes transveisalis has also
an orbicular shield, but the suckers are much less strongly
marked. The use of this organ has been before suffi-
ciently explained

A few words will be necessary upon the folding of the
legs in repose. When insects nsoalk, the thigh is usually
in an ascending position, rising above th^ horizontal line,
the tibia forming with it rather an obtuse angle, and the
tarsus nearly a right one with the tibia; but in the My-
riapods, as far as I can unravel their swift many-footed
motions, these angles in walking do not take place ; m
repose however, in many insects, the coxa forms an angle
with the thigh below the horizontal line and with the tibia
above it, and the tibia and tarsus continue in the same
line, and point downwards nearly vertically ; in others,
as in the Tetramei-ous beetles, the last-mentioned joints

» PMlos. Trans. 1816. t. xx. /. 4, 11. •> See above, p. 305—,

696

EXTERNAL ANATOMY OF INSECTS.

form an angle with each other and turn upwards, the tibia
having an external oblique cavity to permit this ; but the
insects most remarkable for packing close their legs are
those carnivorous genera Dermestes, Anthrenus, Byrrhus^
&c. In the last-mentioned genus there are cavities in
the under side of the trunk, in each division of the
breast, and at the base of the abdomen, to receive the
legs when folded ; the coxcb have also a cavity to receive
the base of the thigh. In the anterior legs this last part
has a longitudinal one on its tipper side, and in the
four posterior on the U7ider, which receives the tibia^
which at the inner edge are straight, and at the outer
curvilinear, and the tarsi are turned up and received by
the concave part, on the anterior side of the Jirst pair
and the posterior side of the two last of the tibice, so as
to lie between it and the body : when the legs are close
packed, the animal looks almost as if it had none. I
have observed that when Dytisci repose on the water,
the posterior legs are turned up and laid over the elytra,
and curved towards the head,

vi. Peotines. I must next say a few words upon a re-
markable organ, which seems in some degree supplemen-
tary to the legs, by which the Creator has distinguished
the genus Scorpio, called from its parallel teeth, set in a
back, their pecten or comb^ This back consists of two
or more articulations, is attached by its anterior extremity
to the sides of the posterior piece of the mesostethium,
and is marked by a longitudinal furrow or channel. The
teeth, which vary in number in the different species, and

Plate XXVII. Fia. 50.

KXTERNAL ANATOMY OF INtiliCTS. 697

in the same species at different periods of its growth, are
usually ovato-lanceolate, or obtusangular, furnished on
their exterior edge with what appears to be a longitudi-
nal sucker, and supported between their bases, or at the
base, bo,th within and without, by triangular, conical, or
subglobose props. With regard to the tiseof these organs,
it has not been clearly ascertained. Amouroux states
that he has seen the animals use them as feet, and he con-
jectiues that by them they may fix themselves and tuz'n
upon them as on a pivot, when they have to make a re-
trograde movement^. M. Latreiile, from their having
branchial pouches imniediately under them, seems to
think that they are connected with respiration''. This
may be true; but ft'om the suckers just described, I am
inclined to think with Amouroux, that they are useful to
the animal in its motions^ and that like the suckers of the
Gecko, flies, &c., they enable it to support itself against
gravity and to climb perpendicular surfaces.

Whether the five obtriangular plates, elevated on a
pedicle, which are found arranged in a series on the un-
der side of each of the jointed coxce of the posterior legs
in Galeodes, are at all analogous to the pectens of scor-
pions, has not been ascertained M. Leon Dufour
watched them very attentively in one species (G. intrepi-
dus\ but he could observe no motion in them"^.

Amouroux Insectes Venimeux, 44.
Observations NouvcUes, Sec. Mem. du Mus. viii. 1 77-
•= N. Diet. d'Hist. Nat. xii. 370.
Descr. dc six Arachnides, &c. Ann ales Gen. ties Scienc. Phys.
1820. 19. /. Ixix./. 7.ri.

LETTER XXXVl.

EXTERNAL ANATOMY OF INSECTS

CONTINUED.
THE ABDOMEN, AND ITS PARTS.

The abdomen of insects, which we are next to consider,
is the third great section of the body, and is the seat of
the organs of generation, as well as of a principal part
of those connected with respiration. My remarks upon
it will be under the following heads : Its substance; ar-
ticulation with the trunk; composition; shape and pro-
portions; {^ appendages; siad. its clothing.

i. Sicbstance. Under this head I may observe in ge-
neral, that where the abdomen is protected by hard elytra
or tegmina, as in most Coleoptera, and many Heteropte-
rous Hemiptera, the upper side is generally of a softer
and more flexible substance than the U7ider, which from
its exposure requires a greater degree of hardness and
firmness to prevent its being injured. In some,— as the
Dynastida: and those beetles whose elytra are connate,
or as it were soldered together, the former is scarcely
more than membrane. In others of the above tribes,
nearly the "Me of the back of whose abdomen, as in Sta-
phylinus; or only its anal extremity, as in Melolontha; or
its sid.es, as in LygcEUS, &c., is not covered by the elytra

EXTERNAL ANATOMY OF INSECTS. 699

or tegniina, that part, as was requisite for its pi-otection,
is harder than the covered portion.

ii. Articulation 'with the trunk. Two distmct modes
of this articulation take place : — in the first the abdomen
is united to the trunk by the nx!hole diameter of its base,
without any appearance of mcision ; in the oth6r only a
small part of that diameter, with a very visible incision.
All the Orders, except the majority of the Hymenoptera
and Diptej-a, and the Ara?ieid(E, belong to the Jirst of
these sections ; for in all these the aperture by which the
abdomen is suspended to the trunk, occupies the whol6
of the base ; I say suspended, because, though in many
cases it inosculates in the posterior cavity of the latter
part, it does not in all, and the margins of the orifice ate
united by ligament to those of that cavity. Indeed, in
the Coleoptera and others that have a somewhat promi-
nent metaphragm^, the trunk may with more pro-
priety be said to inosculate in the abdomen. With re-
gard to the second section, — ^those in which the orifice is
of less diameter than the base, occupying only a portion
of it,' — it may be further subdivided into those whose al)-
domen is sessile, and those in which it is united to the
trunk by the intervention of a long or short pedicle or
footstalk : to the first of these subdivisions belong all
tliose Diptera that have an incision between the trunk
and abdomen — for many tribes of this Order, as the Ti-
■pididce, Asilida, &C., belong rather to the Jirst section—
and the Araneidce the abdomen, however, in all is merely
suspended^ without any inosculation. To the second
subdivision belong all the Hymenopta-a, except the Ten-

Anatom, Covipar, i. 450.

700 EXTERNAL ANATOMY OF INSECTS.

thredinidce and Siricidce, the abdomen of which is united
to the trunk by the whole diameter of its base; these
may be further subdivided into those that have a very
short pedicle and those that have a long one; but as
the mode of articulation in both these is the same,
there will be no necessity to consider them separately.
M. Cuvier has included the Diptera and Araneidce in
the same tribe with such Hymenoptera as have a petio-
late abdomen^; but as the manner in which the latter
articulates with the trunk is widely different from that of
the Diptera &c., I thought it best to consider them as
distinct; especially as in \he Diptera there is no tendency
to a pedicle, while only the above two tribes of Hymeno-
ptera are wholly without it. This learned author thus de-
scribes the articulation where the abdomen is connected
by a pedicle. " They have," says he, " a real solid arti-
culation, a kind of hinge in which the first segment is
■emarginate above, and receives a saliant portion of the
trunk upon which it moves ; this articulation is ren-
dered solid by elastic and powerful ligaments ; muscles
which have their attachment in the interior of the trunk
are inserted in this first segment, and determine the ex-
tent of its movement"." But this passage by no means
conveys an adequate idea of the singular mechanism by
which the Divine Artificer has enabled these little crea-
tures to impart the necessary movements to an organ so
bulky compared with its very diminutive point of attach-
ment As no author that has fallen in my way has ex-
amined the articulation of the abdomen with the trunk in
these Hymenoptera with the attention which it merits

^ Anatoui. Compa): \. -^bl.
De Gcer notices something of the I<ind in Cimbexfemoraia. ii.947.

f.XTF.RKAl. ANATOMY OF IXSECTS.

701

I shall enlarge a little upon it. You would be .surprised,
and not widiout reason incredulous, were I seriously to
assert that these insects lift theii* weighty posteriors
by means of a rope and pulley: yet something like this
really does take place, though not with all in a manner
equally striking. The point of articulation in the insects
in question, except in Evania, is at the base of the meta-
thorax just above the posterior pair of legs: here you see
a small orifice, either insulated or connected by a narrow
opening with the larger one, when the abdomen is re-
moved, which in many instances, as in the common wasp,
is surmounted by another still smaller, through which,
if you examine it attentively, you will find there is trans-
mitted a flat and sometimes broadish ligament or rather
tendon, in which the levator muscles of the abdomen, at-
tached by their other end to the metaphragm*, terminate:
another minute orifice above the base of the pedicle af-
fords a point of attachment to the tendon, so as to give
it prize upon the abdomen. Here the upper orifice in
the trunk is the pulley {trochlea)^, the tendon is the
rope (^funiculus) and the abdomen is the weight to be
lifted. When the muscles contract, the tendon, running
over the edge of the aperture, is pulled in, and the part
just named is elevated ; and when they are relaxed the
tendon is let out, and it falls. Some little variation in
the structure takes place in different tribes : thus, in the

It was omitted to be observed, when tlie supposed pneumatic
pouclies in the genus Vespa were mentioned (see above, p. 585), that
they have also a very conspicuous metaphragm, as probably have
most Hymenoptera, to whi^Ji the muscles that move the wings are
attached.

Plate IX. Fig. 13. F' is the tendon, G' the aperture in the
abdomen C, and a, the aperture in the trunk B.

702 EXTERNAL ANATOMY OF INSECTS.

Formicida, Scoliadce, &c., instead of a separate orifice,
the part I call the pulley is merely an upper sinus of the
large orifice that receives the pedicle of the abdomen.
The shape of these orifices, both of the trunk and abdo-
men, varies in different genera: thus, in the bee it is tri-
angular, with the vertex reversed ; and in the wasp the
upper one is circular, and the lower one transversely ob-
long ; but in all, the apertures of the trunk correspond
with those of the abdomen. In Eva7iia, in which the
minute abdomen is inserted in the upper side of the me-
tathorax, there is scarcely any trace of this structure.
With regard to the articulation of the pedicle itself with
the lower orifice of the trunk, it appears simply sus-
pended, with little or no inosculation. I may observe
under this head, that though the abdomen in almost all
insects is wholly clear of the cavity of the trunk, yet in
some Phalangidce {Gonyleptes K.) it appears ahnost re-
tracted within it».

iii. Composition. I shall next consider the segments
into which the abdomen is usually divided, their num-
ber, and other circumstances connected with them. In
the Hippoboscidce, Acaridce, Phalangidce, and Jrmieida,
the part we are considering is not divided into segments,
though in some instances, as in Gonyleptes and the can-
criform Epeirce^ they are represented hy folds; but ni
the great majority of insects it consists of several dorsal
and ventral pieces or segments, forming by their umon
the annuli or rings into which it appears divided The
number of these abdominal segments varies m different

» Plate XV. Fig. 11. Linn. Tram. xii. t. xxu. /. 16.
^ Surely these Epelrc, of so different a habit from the rest, form
•a distinct genus?

EXTERNAL ANATOMY OF INSECTS.

703

insects; I have noticed more than twenty such variations,
and probably there are many more. Before I give you
them in detail, I must first observe that the dorsal and
ventral segments, though sometimes they correspond in
number, yet very often do not, the dorsal most com-
monly exceeding the ventral by a segment; in a few
cases however the reverse takes place. In the sexes also
there is frequently a difference in the number of seg-
ments, as has been before observed^. I shall express
the variations in question by two figures, the f:rst repre-
senting the number of dorsal segments, and the second
the ventral — they usually only express the apparent seg-
ments: perhaps a very general examination and dissec-
tion might bring many of them nearer to a common
type.

1:1. Chelonus. 6:5. Nepa.

3:3. Chrysidcs^. ^ ^ ^Halictus

4:2. Leucospis". ' (Belostoma.

5:5. Syrphus. CCurculioL.
5:6. Halictus ?. ' iCerainbyx L.

» See above, p. 339.

•» There is reason to suppose that in Chelonus and tlie Chrysidce
several segments are retracted within the abdomen, and if the cavity
of its under side in the latter be examined, it will be cUscovered that
the epigastrimn is divided in the middle into two pieces, and that both
the sides of this and the following segments are covered by three
narrow accessory plates, one to each, the last being the shortest.
De Geer (ii. 833.) describes CVir^sis ignita as having foicr abdominal
rings ; but this is only in appearance, there being really only t/iree.
This appearance is produced by the apex of the last dorsal segment
being more depressed and marked with several deep little excava-
tions that look like holes. In some species of Stilbiim this segment
consists as it were of three ridges or steps.

'^^ In this genus the ventral segments are replaced by a long narrow
central plate, succeeded by a minute one.

701 F.XTEnNAl. ANATOMY Ol' iNSF.rTS.

7:6. Dijliscus^. 9:7. P^r^a Leach ?.

7:7. Ammophila, Sec. 9:8. Perga S'

8:6.

Dytiscus 10:7. Locusta l.e&c\\ ?.

Liicanus, &c. 10:8. <S •

8:7. Geotrupes hatr. 10:10. ^slma.

8:8. Pimpla. 11:7. Phasma.

8:10. Euchlora M'^L. » ? U : 9. Chelifer.
8:13. Scutigei-a. 12:11. Thelyphonus.

9:5. Cflrai02« Latr. Many: Myriapoda.

9:6. Gymnopleunis 111.

1 shall next explain the articulation of the segments
with each other, both that of the rings formed by the
union of the dorsal and ventral pieces, and that of those
pieces themselves. In general it may be stated with re-
spect to the former, that each ring is suspended by liga-
ment to that which precedes it; but this takes place ni
three ways— in some the margins of the suspended rings
touch each other only, with little or no inosculatio7i ;
in others the dorsal segments only touch, and the base
of each venlral is covered more or less by the apex of
the preceding one; and in others again the base of the
whole ring, both above and below, is so covered, or
inosculates. The fa-st kind here mentioned you will
find exemplified in Melolontha, Geotrupes, Musca, &c.;
the second in Scorpio; and the third in Staphylinns, the
Hymenoptera, and many others. In the Coleoptera, says
M. Cuvier, speaking of the movements of the abdomen,
the rings only touch each other at the margin, and the

a In this genus the bed of the posterior coxae appears to consist
of two segments, which are beautifully fringed with parallel short
bristles.

EXTERNAL ANATOMY OF INSECTS. 705

movement is very limited ; whilst in the Hymenoptera
they are so many little hoops, which inosculate in each
other as the tubes of a telescope, one third only of
their extent often appearing uncovered^. We see the
reason of this structure wheh we consider the calls they
have for greater powers of movement in this part in lay-
ing their eggs, and annoying their enemies and assail-
ants ; and also in the Staphylinicla; to enable them to
turn up their abdomen like a scorpion, both as a posture
of attack, and to fold their wings : in all cases, however,
as far as my observation goes, these animals, when they
want to lengthen this part, can disengage the rings from
almost all inosculation, so that no impediment remains
to any movement.

The articulation of the dorsal and ventral segments
with each other is next to be considered. In luhis
and some Centroti the ring appears to be formed of
a single piece, with scarcely any trace of the existence of
any such division ; it is however almost universal, and is

three descriptions; in the first the dorsal segments are
united to the ventral at the lateral margin or edge of the
abdomen; in the second it is above this margin, and in the
third helo-iS) it. You will find that in Fulgora and many
other Homopterous Hemiptera these segments unite at
the margin, as they do likewise in Cimex lecfularius be-
longing to the other Hemipterous section ; but in the
rest of the Heteropterous tribes, the ventral segments
turn upwards, and their union with the dorsal is in the
back of the abdomen ; in these the Hcmelytra and wings
only cover the dorsal segments, leaving the edge, formed

' Anafoin Compar. i. 451.
vol,. Ill, z

70Q BXTERNAI^ ANATOMY Of INSECTS.

of the ends of the ventral, uncovered. The LameUi-
corn beetles also, and many other Coleoptera, exhibit the
same structure. To the last description, in which the
dorsal segments turn down to meet the ventral, belong
the Lepidoptera, Locusta Leach; likewise .S><?jr, Chrysis,
and many other Hymenoptera. The articulation between
these segments is by means of an elastic membranous
ligament, which usually is not externally visible; but in
mtny instances, in which the connecting ligament is of a
firmer substance, as mScorpio, Thelyphonus, andPhrynus,
it ia very conspicuous, and in the latter genus exhibits
many longitudinal folds, as it does likewise in Gtyllo-
talp.ay which must permit a vast extension of the abdo-
men. In this membrane, in some cases, as in Dynastes
WU, Melolontha, &c., the two or three first spiracles
are fixed ^ In the Hymeyioptera and many other insects
the dorsal segments do not unite by their margin with the
ventral, but the end of each dorsal laps aver that of the
corresponding ventral.,

Dorsal segmenisK I shall next notice the segments
seriatim, in the order of their occurrence, beginning
with the dorsal ones. The most remarkable circumstance
with respect to these that occurs to my recollection take^
place in the Cancroid spiders {Epeira cancriformis, acu-
leata, &c.), in which the back of the abdomen is formed
by a plate, in some extended in a transverse du'ection
CE. cancriformis), in others in a longitudinal one {E.
acideata), of a much harder substance than the under
side and quite flat, set with strong sharp spmes, m the
former species appai'ently moveable, and termiuatmg be-

a Pr^TEVni.Fio.9. ^".5'. " Ibid. F,G. 5. X.

EXTERNAL ANATOMY Ot IKSfiCtS. 7dt

hind in a piece resembling in some measure the scutellurii
of the Stratyomida: and similarly armed with a pair of
spines * : in ^B. aculeata the sides of the abdomen, un-
der the plate, have a humber of longitudinal folds lik6
those of Phrynus, In C^-yptoceruSi a genus of ants pecu-
liar to South America, the Jirst segment, not reckoning
the pedicle, forms almost the whole back of the abdomen,
and the three last are so minute as scarcely to be distin-
guishable. Nothing very remarkable is exhibited by th6
other segments, except that in Trichius the penultimate
is the largest; in some Staphjlinidce {S. splendens) and
Brachini ( B. melanocephalus) it is emarginate, and in the
former fa'ibe also often terminating in a white membrane.
The dorsal segment most worthy of notice is the last, which
is called the podex ; for though in general it is a minute
piece, often retracted within the abdomen and invisible?,
as in many Diptera, yet sometimes it is the most con-
spicuous of the dorsal segments. It is most commonly
ti-iangular, and usually deflexed and forming an angle
with a horizontal line; but in Clytra, Chlan^ys, and
Oryctes, it is inflexed ; in many Lamellicorns it is nearly
vertical. In Tettigonia F., many other Homopterous
Hemiptera, and some Hymenoptera {Cimbex), its sides
turn down and become ventral ; on if6 lower side it has
in these a longitudinal cavity which receives the oviposi-
tor in repose''. In many other insects it unites with the
last ventral segment, the hypopygium^ to form a tube
for that organ, as you will find in Callidium violaceum <=,
many MuscidcSy and Thelyplionus. As to its termination
the podex is sometimes bifid, Blatta; bipartite, Ranatra;

' Plate XV. Fio. 10. b Reaum. v. t. xvit./. 14 a. a.

' Linn. Trans, v. t.xn.f. 13.

2 z 2

708 EXTERNAL ANATOMY OF INSECTS.

mucronate, Si7'ex; acuminate, Melolontha vulgaris, Tri-
chhis hemipterus. Generally this part is flat ; but the disk
is elevated or gibbous in Onjctes and some other La-
mellicorns. In the majority of the Coleoptera Order it
is quite covered by the wings and elytra ; but in many of
the last-mentioned tribe, and sometimes the penultimate
segment also, it is not covered by them'*. In some in-
sects the piece we are considering appears to consist of
two segments; in the male of Lociista morhillosa the
whole podex is rhomboidal, but it is formed by two tri-
angular pieces which articulate with each other; this
structure permits the more easy elevation of the termmal
one for the extrusion of the feces.

Ventral Segments ^ We are now to turn our atten-
tion to the ventral segments of the abdomen. The first
of them is what is called the epigastrium^ in the table.
This part, according to M. Chabrier, is of considerable
importance to the animal in flight, as, by its pressure
against the trunk, not only regulating the movements of
the abdomen, but as, in his opinion, contributing to push
forward the trunk^ in the descent of the animal. It is
remarkable only in the Coleoptera and Heteropterous
Hemiptera, to which my observations upon it will be
confined. It may be stated as usually consisting of two
articulations, that nearest the trunk being narrow, and in
the Predaceous beetles % as also in Scutellera, Pentatoma,

» Daklorf Society" s Trans, vii.) has divided Geotrupcs into

two families, one with the podex covered {G. vernaHs, &c.) which he
calls modesii, the other with it uncovered (G. stereomrius, &c.) which
he calls obscceni. " Pi-ate VIII.

e iijjj 2)' Sur le Vol des Ins. c. i. Addend. 299.

« In Dt/tiscus marginalis the upper side of the margin of the Hy-
pochondria is curiously cut into transverse corrugations.

EXTERNAL ANATOMY OF JNSECTS.

709

&c., interrupted in the middle =*. In many Lamellicorns
this joint is concealed lender the posterior coxce, and with
the anterior part of the second forms a hollow cavity for
their reception ; this last joint is what is properly the
Epigastintm, the former, especially when distinct, being
called in the table the Hypochondria. In Sagra and
Brentns the epigastrium is particularly conspicuous for
its size, in the former occupying half, and in the latter
nearly two-thirds of the under side of the abdomen; but
in general it is distinguished from the remaining segments
only by the central mucro or point that terminates it
towards the trunk'', and which is received by a sinus of
the metastermim ; this point is generally minute and tri-
angular, but in Sagra it is large and rounded at the
extremity, and in Calandra it terminates nearly, in a
transverse line somewhat waving. It is most remarkable,
however, in some species of the Heteropterous genus
Edessa F. for in E. nigripes and affinities it is a sharp
sterniform conical horn, which passing between the four
posterior legs covers the end of the promiscis. In fact,
this part appears a kind of abdominal steimum. In the
Cetoniadce, &c., Hypochondria unite before this mucro,
and form a ridge which articulates with it, and dips
towards the abdominal cavity ; in Scolytus the epigas-
trium is much elevated from the rest of the ventral seg-
ments, so that the under side of the abdomen appears as
if it were suddenly cut off, whence Herbst's awkward
though not inexpressive name, Ekkoptogaster ; this part
in this genus has something of a posterior mucro.

The intermediate ventral segments exhibiting no very

" Plate VIII. Fig. 6. C . * Ibid. B '.

710 EXTERNAL ANATOMY OF INSECTS.

remarkable peculiarities, I shall pass them without fur-
ther notice, and call your attention to the last, which is
opposed to the jwdesc, and which I have named the
jpppygium^. Though usually a single small piece, in
Ed^ssa and many Pentatovice it consists several plates;
and in Trichius it is very large : it is mostly intirCi but
in the male Dytisci it is cleft; in Lamia ocellata trilobed ;
in jBdessa tripartite; in Centrotus Taurus it is boat-
shappd and hollowed out to receive the stalk of the ovi-
positor. It is also generally in the same line with the
body, but in Xenos it is tiirned up and bentmwards^

iv. Shape. With regard to shape, in some Orders the
abdomen varies considerably; but the most general form
is on^ that approaches to trigonal, so that a transverse
section will be a triangle, with the vertex more or less
obtuse, and the base more or less convex; some tendency
tp this form will often be found even in those insects whose
abdomen appears almost as flat as a leaf, as in many
^adi. In the hive-bee the transverse section is ahnost
an equilateral triangle ; in Belostoma grandis the disk of
under side of the part in question is longitudinally
elevated into a trigonal ridge, the section of which is an
equilateral triangle, the sides bemg quite flat. In gene-
ral, in the vertical section of an abdomen, the vertex of
the triangle points dow^iwards, but in Lihelhda F. it
points upxioards. In Blatta this section is nearly lanceor
late ; in StaphyUmis olens it is a segment of a circle with
t|he convex side downwards; mMshna F. with that side
upwards; and in Agrion the section is circular. In
^opris, Jteuchusy &c., the abdomen is very short and

» Plate VUl. L'.

>> Linn. Trans., xi. t. ix./. 15-

EXTERNAL ANATOMY OF INSECTS. 711

thick; mStaphylinus slendef and long; \nAradus, Nepa,
&c., depressed and flat; compressed in Ophion and
Evania: conical in Ccelyoxis; rhoraboidal in many
Mantes; boat-shaped in many Z^T/g^f ; fusiform in various
PapilionidcE; lanceolate in some Mneumonidce, falcate
in others ; nearly round in Diapria purpwascens ; ovate
in Lyrops ; elliptical in Andrena; oblong in many Xylo-
copes ; heart-shaped in the naked EuglosscB; triangular
in Dytiscus; gibbous in Flata; and vaulted in Chysis.
At its base it is truncated in Sirex; retuse in most beesi
forming the segment of a circle in Andrena ; in general
sessile, but in the majority Hymenoptera, as has been
already observed, terminating in a pedicle. The pedicle
is very short in the Andrenidce and Apida ; long in the
SphecidcE; thick in the Formicidcc; sle: -^f&r in Evania;
fusiform in Pe/ecmws; c\maX& in Ammophila; campanu-
late in many VespidcS; nodose in Myrmkd" ; squami^
gerous in Formica^ : it sometimes also consists of fwo
joints, as in Ammophila and many Vespida. As to
margin, some have none, as Centrotus ; in others, as-
Dytiscus, it is very narrow ; in others again, wide and
flat, as in the Nepidcc; in Staphylinus, &c, it is distin^
guishable only on the upper side of the abdomen ; in
Lomsta Leach only on the under side, though mostly
intire ; it is serrated in Blatta, sinuated in Acanthia pa-
radoxa, and crenated in Cerceris.

V. Proportions. These vary greatly in the difierent
tribes; in some the abdomen is long and slender, as in
Locusta, and Staphylinus; disproportionably so in a re-
markable degree in some Agrionida from South America,

» Plate IX. Fig. 18. /'. " IWd. f iG. 17- H'.

712

EXTERNAL ANATOMY OF INSECTS.

as A. lineare, &c. * ; in others it is extremely sliort and
thick, as in Copris, &c.; a mere appendage in Evajiiu;
it is shorter than the elytra in Trox ; of the same length
in most beetles ; longer in Melolontha^ Hister, &c.; dis-
proportionably so in Staphylinus: though usually of the
same width with the trunk, in many Mantidce it is much
wider''; and more slender in the LihelluUna, Myiine-
leon, &c.

vi. Arms and Appendages^. These are various ; and
maybe considered under the following heads : processes,-
organs of respiration^ motion and prehension; weapons;
and other anal appendages the use of which is unknown.

1. Processes. Under this term I include all promi-
nences of whatever kind, whether tubercles, teeth, spi?ies,
or ho7-ns, that m any part of the abdomen. Many of
these are sexual characters, and have been sufficiently
described in a former letter'*; I need not therefore detain
you long on this head. Of the first kind is a remarkable
elevation that distinguishes the second ventral segment
oiScolytus Destructor {Ips Scolytus Marsh.) or of a species
allied to it^; in S. pygmczus {I. midtistriatus Marsh.) die
same segment is armed by a flat horizontal tooth or horn;
in an Aradus from Brazil, before alluded to ^ {A. lami
natus K. MS.), the margin of the abdomen is surrounded
by eight flat subquadrangular laminae; in another species
figured by StolU, it is cut out into bays by a number of

» Rcemer. Genera, &c. t. xxiv./. 4. " Stoll Siiedr. t. vii.
Plate XV. Fig. 10-23. See above, p.339— .

« This tubercle I find only in a specimen from Sweden, sent to me
by Major Gyllenhal, but not in any British one I possess. In this spe-
cimen the declivity before mentioned (see above, p. 709.) is observa-
ble in the/;-ii! segment, but in the others it is formed by the second.

f Sec above, p. 617. ' Punaiscs, t. xiii. /. 84.

EXTERNAL ANATOMY OF INSECTS. 713

denticulated teeth ; and in Acanthia paradoxa by long
spinose lobes*. In Edessa F., another genus of bugs,
the abdomen usually terminates in four strong sharp
dentiform spines, the intermediate ones being the short-
est, and in some the margin is also armed with spines'';
occasionally the anal spines are very long*=. In addition
to the ventral horns before mentioned that distinguish
the sexes of some insects'*; the males of the genus ConopSf
a two-winged fly, have, on the antepenultimate ventral
segment, a singular process, varying in length and shape
in the different species, standing nearly at right angles
with the belly, convex towards the trunk, and concave
towards the anus. De Geer supposes that with the anal
extremity this forms a forceps with which this fly seizes
the other sex ^.

2. Organs of respiration ^. I shall defer my account
of the spiracles, and other external respiratory organs,
till I come to treat of the system of res^nration in insects,
when every thing connected with that subject will be
most properly discussed ; but there are certain appear-
ances in some insects, which at first sight seem to par-
take of the same character, but which being really inde-
pendent of that vital function, may here have their place.
If you examine the abdomen of the mole-cricket {Gri/llo-
talpa vulgaris), you will easily discover the true spiracles
in the folds of the pulmonarium, which separates the back
of that part from the belly ; if you next inspect the five
intermediate segments of the latter, you will discover
on each nearer the base a pair of oblicjue little chan-

" Stoll Punaises, t. xiii. /. 101.

'■ Ibid. ^ xxxvi./. ?53.

• De Geer, vi. 260. xv./. 8. d.

b IMd.t.yi\\\.fA\7.

See above, p. 339 — ,
f Plate XXIX.

714

EXTERNAL ANATOMY OF TNSECTS.

nels, which precisely resemble closed spiracles. These
may be denominated false or blind spiracles. Again, if
you examine the pupa of any Scutellera or Pentatoma,
in which tribe the true spiracles are ventral^ you will
discover, placed in a square on the two or three interme-
diate dorsal segments, four or six elevated points resem-
bling spiracles, but not perforated, connected often by
corrugations in the skin or crust*; in the larvae also of
some Jtedumi the first minute dorsal segment, at each
lateral extremity, has a similar elevation with a central
umbilicus precisely resembling a spiracle, but still not
perforated : another instance of false spiracles in this sec-
tion the Hemiptera, is furnished by Aradus laminatus
before mentioned, in the perfect insect; between the
spiracle and the margin of each ventral segment is a
white round callus, with a dark point resembling a
perforation on its exterior side, and terminating inter-
nally in a channel covered by membrane leading to the
disk of the segment, so that the whole in shape resem-
bles a tobacco-pipe''. A number of similar callosities
with a central impression, but without any channel, va-
riously disposed, are also to be found in another bug,
Bhinuchus compressipes K.<= In the Homopterous sec-
tion of this Order, a series of impressed points, which
may be easily mistaken for spiracles, are to be discovered
on both sides of the abdomen, at the margin in Centrotus,
in which the real spiracles are quite concealed.

In spiders, as we learn from Treviranus, the open ven-
tral spiracles of the scorpion are replaced by pseudo-

•■^ Plate XXIX. Fig. 22. is part of the back of the abdomen of the
pupa of a Pentatoma. a the pseiido-spii acle, h the connecting corru-
gations. " fbid. Fig. 24. a. ' Ibid. Fig. 2/. a.

EXTERNAL ANATOMY OF INSECTS. 715

spiracles ; these in Epeira Diadema are three pah' of small
black pomts: on the back of the abdomen also are fmir
pair, but in some species there are only two^: the most re-
markable, however, are exhibited by the cancriform spi-
ders before noticed'': in Epeira cancriformis, in the plate
which covers the abdomen, they are dark red spots with
an elevated rim and centre <= exactly resembling spiracles,
except that they are not perforated ; there are twenty-
four of them, twenty arranged round the mai'gin, and
four in a square in the disk.

3. 07-ga7is of motion. In a fonner letter you were
told that several insects are enabled to leap by means
of orgafis in their abdomen ; I shall now describe such
of them as require further elucidation. I then said that
Podura and Smintlmrus, two apterous genera, take their
leaps by means of an anal fork'^. In the former genus
the fork consists of a single piece attached to the under
side of the anus, and terminating in a pair of long slender
sharp processes which articulate with it and form the
fork or saltatorious instrument ^. In Sminthwus the tines,
as they may be called, of the fork do not articulate with
the base, but are of the same piece and consist of two
joints, the terminal one being flat and obtuse ^ . Machilis
to the anal fork adds eight pair of ventral linear springs
{Elastes% which are covered with hair or scales, and ter-
minate in a bristle or two. I have on a former occasion
mentioned the natatorious laminae with which the anus

» Treviranus. Arachnid. 23 — . * See above, p. 702, 706.

« Plate XXIX. Fig. 26. represents one of them,
" Vol. II. p. 319— .

' Plate XV. Fig. 14. M". De Geer, vii. t. ii. /. 5, 10,21.
f Ibid. L in. /.4, 14.

716

EXTERNAL ANATOMY OF INSECTS.

of the larva o^Agrion and of some Diptera is furnished*;
the same part in that of Dytiscus ends in a pair of taper-
ing organs, fringed on each side like the hind-legs of the
imago'', which doubtless assist it in swimming; those
respiratory foliaceous laminae which so singularly di-
stinguish the abdomen of the larvae of Ephemera^ like the
legs of the Branchiopod Crustacea^ are probably used in
some degree as fins, and aid their motions in the water
Under this head may also be mentioned the many-jointed
brisdes that form the long tails'^ of the fly that pi-oceeds
from these larvae, whose interesting history I long since
enlarged upon ; for when they fly the two lateral ones
diverge from the central one, and perhaps perform the
same office as the tail feathers {rectrices) of birds. These
bristles are also to be found in MacJiilis^i and probably,
as its leaps are almost as long as Jlights, for a similar
purpose, to steady their motion. I may here lastly state
that I once saw a Cryptophagus [Corticaria Marsh.), but
I forgot to note the species, walking upon my window,
which when it wanted to turn fixed itself to the glass by
an inflated anal vesicle, and so accomplished its purpose.

4. Organs of Prehension^ . The abdominal organs of
prehension are various ; but as the great body of them are
connected with the sexual intercourse of insects, I shall
not consider them till I come to treat on that subject.
The only remarkable one that is common to both sexes
is that of the earwig, which is too well known to every
child to call for any long description. The external or-

' See above, p. 154. Plate XVIII. Fig. 5. a.

'= Plate XXIX. Fig. 3, 4. De Geer, ii. /. xvii. /. 12. and 1. xviii.

/ 2. J Ibid /. xvi. /. 8—13.

' Plate XV. Fig. Hi. S'. ' Ibid. Fig. 12. L".

EXTERNAL ANATOMY OF INSECTS. 717

gans of oviposition I shall also describe hereafter, and
likewise those .of secretion that have not already been
noticed.

5. Weapons. As the stings of some Hymenoptera are
analogous to the ovipositors of the majority of that Order,
I shall consider them both together when I treat of the
sexual organs of insects; but there is one, and that a tre-
mendous one, not connected with those organs, which
may be noticed here. I mean the sting of the scorpion.
There appears to be some analogy between the poisonous
fangs of one tribe of the Ophidian reptiles % the mandi-
bulae of spiders'', the second pair of pedipalps, or the
fangs of the Scolopejidrida", and the organ in question'';
but the last possesses this peculiarity, that it is placed at
the opposite extremity of the body, where it is preceded
by a long jointed tail, which properly speaking is merely a
continuation of the abdomen, since the spinal marrow, the
intestinal canal, and the pseudocardia, are extended into it ^
Providence might have a double view in thus contracting
the dimensions of this part of the abdomen ; in the first
place, the animal is by this enabled to turn its tail over its
back preparatory to its inflicting a wound, and in the se-
cond, perhaps, this formation favours the sublimation of
the venom, the long tail acting as an alembic for that
purpose. This machine consists of six angular joints in-
cluding die sting, the last but one being the longest, and
the last inflated, as it were, at the base, and terminating
in a sharp subulato-conical point which curves down-

» Pkihs. Tram. 1818. t.xxn.
N: Diet. (THht. Nat.ii. 273—. Iloole's Lecmvenh. i. t. \\.f. 10. 1.
Lceuwcnli. F.jmt. 17. Octobr. 1687. / 10. C.
Hoole's Lecuwenh. i. I. v./. 12, 13. " Treviranus, Arach. 4.

716

EXiTERNAL ANATOMY OF INSECTS.

wards, and has an orifice in a channel at the end on each
side. Treviranus could not discover these orifices in the
sting of Scorpio europcsus^ ; they may however be readily
seen if viewed with a sufficiently high power, though not
under a common pocket microscope. Whether the very
slender, many-jointed, real tail of the remarkable genus
Thelyphonus is used in any respect as a weapon, has
not been ascertained : it is a fihform hairy organ consist-
ing in some specimens of more than twejity joints, the
first being very much larger than the rest''.

6. Appendages'". We are lastly to advert to those
appendages of the abdomen of which the use is not at
present discovered. These are the styles {styli) of the
Stapliylinidce ; the leaflets {foliola) of the LibeUulina;
the floret {Jloscidus) of the FulgorcB ; the cerci of the
Blattidce and Gryllina; and the threads {Jila) of Ma-
chilis: but having nothing important to add concerning
them, the definitions of those terms will give you a suf-
ficiently clear idea of them^. As they are common to
both sexes, if their use is connected with the sexual in-
tercourse, it must be similar to that which Treviranus
ascribes to the pectens of scorpions, they must be m-
struments of excitement.

And now, after this long discourse on the External
Anatomy and structure of these little beings, you may
think perhaps at first that the subject is exhausted ; and

* Treviranus, Ji&zsMj)?'. 14.

" In my specimen including the first joint there are tiuenty, and
some seem to have been broken off. In Rcemer's figure {Genera,
t. xxix. /.II.) there are only ten. Perhaps they vary m number ac-
cording to the age of the animal.

Plate XV. Fig. 13, 16, 17- " See above, p. 391- .

EXTERNAL ANATOMY OF INSECTS. 719

that I must have discovered and described every part
and every variation of every part of the crust of an insect.
But when you go on to reflect what a comparatively
small number of these creatures have fallen under my
examination, and in those, after all my laborious and
painful researches, from my limited faculties and other
imperfections of our common nature, how much will
probably have eluded my notice, you may conclude that
thousands of facts still remain concealed to reward the
patient assiduity of future investigators. Such are the
immensity and variety of the works of the Creator in
this department, that it would require a long life, and
fill volumes upon volumes, to discover and give a de-
scription of all the peculiarities of structure of the insects
that are already known ; and could all that exist * be so
studied and explained in full detail, the library that the
Calif Omar ordered to be burned at Alexandria could
scarcely have contained more books than would be re-
quired to receive the results. But " who is sufficient
for these things ^ ?" This is a question that the most able
and most experienced physiologist must often feel dis-
posed to put to himself when, lost in the intricate laby-
rinth of the works of his Maker, he sees all things ar-
ranged, " wheel within wheel," in an order that he can
only partially unravel, instead of tracing the " regular
confusion" through all its windings. But glimpses of
light, and points of irradiation, here and there discover
to him fragments of the truth of things, and such vestiges

» I have heard it stated upon good authority that 40,000 species
of insects are already known, as preserved in collections. How great,
then, must be the number existing in this whole globe !

^ 2 Cor.ii. 16.

720

EXTERNAL ANATOMY OF INSECTS.

of the grand system of the Deity, as enable him in some
degree to appreciate, and dispose him humbly to adore
that Wisdom, Power, and Goodness, that at first
created and now sustains in its full beauty and harmony
the wondrous whole.

I am, &c.

end of the third volume.

Printed by llichavcl Taylor,
Shoe- Lane, London.

EXPLANATION OF THE PLATES ^

PLATE VI. "

FIG.

1 . Head of Mylabris. Upper side, or face.

2. . ~ Under side, or subface.

3. Trophi of Dytiscus. Six pieces.
4;. Head of Locmia. Face.

5. Front view, to exhibit the mouth.

6. Trophi of ditto. Seven pieces.

7. Head of Cicada. Face.

8. Scutellera. Subface.

9. Trophi, or promuscis of Hemiptera. Three pieces.

10. Head of Mshna. Face. • '

11. Front view.

12. Trophi of ditto. Seven pieces.

13. or antlia of Lepidoj^tera. Fotxr pieces.

14.. of Panorpa. Three pieces.

PLATE VH.-^

1. Head and trophi of Phryganea L. Face.

2. Vespa Crabro. Ditto.

3. Trophi of Bombus.

4. Head of Tabanus L. Face.

5. Trophi or proboscis of ditto. (Reaum.)

6. Bombylius'^.

7. Head of Oxypterum. Face.

* Recourse must be had to the synoptical table of the noftiencla-
ture of the parts of the external crust of Insects (Vol, III. p. 354; for
the explanation of the reference letters not here given.

" Vol. I. p. 394-. III. p. 355—, 394-. IV. p. 305—.

' Ibid. " Probably e' is resolvable into two pieces.

VOL. in. 3 A

722

EXPLANATION OF THE PLATES.

FIG.

8. Head of PuleX, with its antennae and trophi, or rostruhm.

Side view.

9. Araneidce, with the trunk.

10. Trophi of ditto.

\i. ^e2idi Scolopendra morsitans, Subface.

. -■ — Front view, to show the

mouth.

13. Trophi of ditto.

14. Pharynx of Pentatoma. (Savigny.)

PLATE VI1I.»

1. Prothorax of L?/caw<s. a. Apex. b. Base, c d. Sides.

a. Disk.

2. Antepectus of ditto.

3. Alitrunk of ditto. Upper side. a. A piece between the

metathorax and metaphi agm.
4,, . — Under side.

5. Abdomen. Upper side, or tergum.

6. _ .. Under side, or venter.

7. Antepectus of Hydrophiliis piceus.

8. AUtrunk of ditto. Under side, to show the metasternum.

9. Abdomen of Dynastes Aloeus, to show the dorsal and

ventral spiracles.

10. Prothorax of Locusta. a. Apex. b. Base, c c. Sides.

11. Antepectus of ditto, to show the prosternum.

12. Alitrunk of ditto. Upper side.

13. Underside.

14,. . . . Lateral view. Vol. III. p. 48.

15. Abdomen of ditto. Lateral view.

16. Alitrunk of Cicada Latr. Upper side.

. ^ Underside, a. The piece in the

$ corresponding to the drum-covers of the ^.
18. Abdomen, and part of postpectus of ^ ditto. Under
side, to show the drums. Vol. II. p. 405 — .

» Vol. III. p. 367—, 529— IV. p. 326—

EXPLANATION OF THE PLATES.

723

FIG. ;V

19. Abdomen, and part of postpectus of ^. Lateral view,

with the covers removed to show the machinery,
aO. Alitrunk. Upper side. Pentatoma,

PLATE IX.*

1 . Alitrunk of Cossus ligniperda. Upper side.

2. Part of ditto, to show the mesophragra.

3. ■ Under side.

4. V^Lt2igmo^ Lepidoptera. Upper and under sides. Vol. IIL

p. 368, 539.

5. Tegulae of ditto. Txuo species. Vol. IIL p. 378.

6. Prothorax JEsIma. a. The base elevated and forming

an obtuse angle with the rest.

7. Alitrunk of ditto. Upper side. a. Two elevated areas

of the posterior parts of the collar, strengthened by a
marginal ridge and denticles, internally connected by
an elastic ligament, apparently to aid and sustain the
powerful action of the wing-muscles,

8. I Lateral view, a, A piece by which

the mid-leg is connected with the scapular. Vol. IIL
p. 48, 565.

9. Part of the abdomen of Libellula.

10. Trunk of Semblis F. Upper side.

11. Alitrunk of Vespa Crabro. Upper side. a. Aperture in

the trunk for the passage of the ligament that elevates
the abdomen.

12. Lateral view of ditto,

13. posterior part of ditto, and of the base of

the abdomen, to show the above apparatus, a. The
aperture. Vol. III. p, 701,

14. Head and part of the manitrunk of Tenthredo L. to show

the membrane a. representing the prothorax. Vol. IIL
p. 550—,

" Vol. hi. p, 367—, 529—, IV, p. 326-.
3 A 2 ^

724

EXPLANATION OF THE PLATES.

FIG.

15. AHtrunk of Xiphydria. Upper side.
. -- Lateral view.

17. Part of trunk and abdomen of Formica, to show the

squama. Vol. III. p. 389. 3.

18. ■ ■ '■ — of Myrmica, to show the no-

dus. Vol. III. p. 389. 4.

19. Alitrunk Musca. Upper side. a. Alula or winglet.

20. Metathorax of ditto.

21. Alitrunk of ditto. Lateral view.

22. Abdomen of ditto. Venter.

PLATE. X."

N.B. In this plate the red points out the costal, and the
yellovo the anal areas, the intermediate being unco-
loured.

1. Elytra, a. Base. b. Shoulder, c. Lateral margin.

d. Apex.

2. Tegmina. Blatta.

3. Hemelytra. Pentatoma.

4. Wing, Coleoptera. a. An insulated nervure. Vol. III.

p. 625. .

5. . — Dermaptera.

6. Lepidoptera.

7. . Neiiroptera.

8. Hymenoptera. Tenthredo L.

9 . Bombus.

10. Under wing. Hymenoptera.

Y\ . ■ Proctotrupes.

12, — — Diptera. Tipula.

23 , Psychoda. Vol. III. p. 645,

. Musca. a b. Two areolets be-
tween the costal and mediastinal nervures. c Areolet
between the mediastinal and postcostal nervures.

Vol. II. p. 347— HI. p. 372-, 595-

EXPLANATION OF THE PLATES.

725

d. Areolet between the postcostal and subcostal ner-
vures. e. Open areolet. Vol. III. p. 634?.
15. Under wing. Diptera. Strattjomis. ab. The two areo-
lets between the costal and postcostal nervures ; the
mediastinal being 'nearly obsolete, c. Middle areolets

crowned by a small one,

PLATE XI.

Antennce.

FIG. FIG.

1. Setaceous.

13. Distichous.

2. Capillary.

14. Pectinate.

3. Filiform.

15. Duplicato-pectinate.

4. Incrassate.

16. Ciliate.

5. Fusiform.

17. Flabellate.

6. Prismatic.

18. Ramose.

7. Ensiform.

19. Furcate.

8. Falciform.

20. Auriculate. a. The auricle.

9. Moniliform.

21. Palmate.

10. Dentate.

22. Irregular.

11. Serrate.

23. Perfoliate.

12. Imbricate.

PLATE XII. AntenncB.

FIG.

1. Capillaceous.

9. Capitate with a solid

2. Mucronate.

knob.

3. Uncinate.

10. Capitate with a perfo-

4. Clavate.

liate knob.

5. Nodose, or Biclavate.

11. Filiform.

6. Convolute.

12. Globiferous.

7. Geniculate.

13. Connate.

8. Capitate with a tunicate

^^' \ Setigerous.

knob.

15./ "

Vol. III. p. 366, 510— IV. p. 316—.

726

EXPLANATION OF THE PLATES.

FIG.

16. Subulate.

17 ■)

* J- Filate, simple.

1 8. J

19. Filate, compound.

a. Joints.

20. Filate.

21. Aristate. Setarious.

a. Bristle.

22. Aristate. Plumate.

a. Bristle.

FIG.

23. Stupeous. Vol. III.

p. 646.

24. Plumose,

25. Scopiferous. a. Brush,

26. Barbate,

27. Verticillate.

28. Inflated.

29. Auriculate. a. Auricle.

PLATE XIII.-

1. Unguiculate feeler. Gonylep.es. a. Claw.

2. Securiform ditto. Cychrus. a. Terminal joint.

3. Inflated ditto. Araneida: (J. a. ditto.

4. Lunulate ditto. Oxyporus. a. ditto.

5. Dentate mandible. Megachile.

6. Suctorious ditto. Larva of Dytiscus. a. Aperture.

7. Prosthecate ditto. Staphylinus. Vol. III. pp. 356, 439.

8. Trophi of Curculio L.

9. Pedunculate eyes. Diopsis. a. Footstalk.

10. Compound ditto. Muscidce. Vol. III. p. 494. 3.

11. Conglomerate ditto. Mus. Ibid, p. 494. 2,

12. Rostrate head, Balaninus.

13. Capistrate ditto. Nitidula.

14. Clypeate ditto. Copris.

15. Lychnidiate ditto. Fidgora.

16. Buccate ditto, Myops. a. The inflated part.

17. Cruciate prothorax. Loaista.

18. Cucullate and alate ditto. Tingis.

19. Subulate elytra, Sitaris.

20. Ampliate ditto. Lycus.

Vol. IV. p. 307. iii. iv. 309- b. 310. d. 313. viii. 328, 334.

EXPLANATION OF THE PLATES.

727

PLATE XIV.

IG.

1. Ideal wing, to exemplify painting. Vol. IV. p. 286 — .

a. Anterior or exterior margin. b. Interior ditto,
c. Posterior ditto, d. Humeral angle, e. Scutellar
ditto, f. Posterior ditto, g. Anal ditto, a. Articulate
/a.scm, or band. 6. Macular ditto, cc?. Sesquialterous
ditto, de. Sesquitertious ditto. /. Dimidiate ditto.
g. Abbreviate ditto, h. Pyramidate ditto, i. Super-
ciliura. k. Hastate pupil. L Compound eyelet or
ocellus, m. Nictitant ditto, n. Simple ditto, o. An-
nulet, jj. Bipupillate eyelet, q. Sesquialterous ditto,
r. Double ditto, s. Caudate wing. t. Pupil, u. Iris.
V. Atmosphere.

2. Reversed wings. Gastrophaca.

3. Digitate ditto. Pterodactylus.
4*. Falcate ditto. Attacus.

5. Saltatorious leg, with loricate thigh. Locusta.

6. Natatorious ditto. Dytiscus.

7. Ambulatorious ditto. Lucanus.
S. Prehensorious ditto. Gonyleptes.

PLATE XV."

1. Laminate coxa. Haliplus.

2. Alate tibia. Lygccus phyllopus. a. The appendage.

3. Clypeate ditto. Crabro $. a. The clypeus. Vol, III.

p, 334.

4. Dolabriform ditto. Curculio marithnus E.B.

5. Fossorious leg, with palmate tibia, Clivina. Vol II.

p. 365.

6. with digitate ditto. Gryllotalpa. Ibid,

p, 366.

7. Chelate feeler. Scorpio.

8. Scutate tarsus. Hydrophilus piceus Vol. III. p. 336.

9. Patellate ditto. Dytiscus marginalis $. a. Cups, Ibid,

p. 336, 694—,
" Vol. IV. p. 286—, 338, 345—. " Ibid. p. 345-, 350—,

728

EXPLANATION OF THE PLATES.

FIG.

10. Obumbrate ahdomen. Epeira cancriformis.
] 1 . Retracted ditto. Gonyleptes.

12. Cheliferous tail. Panorpa S-

13. Flosculiferous ditto. Fulgora.

14. Saltatorious ditto. Podura.

15. Folioliferous ditto. jEshna.

16. Cauduliferous, and filiferous ditto. Machilis.

17. Styliferous ditto. Staphylinus.

18. Unciferous ovipositor. Locusta.

19. Ensate ditto. Acrida.

20. Navicular ditto. Cicada.

21. Serrulate ditto. Tenthredo L.

22. Telescopiform ditto. Chrysis.

23. Anal apparatus of BlaUa.

PLATE XVI. «

1 . Extricated ovipositor. Pimpla. Two pieces.

2. Telescopiform ditto. Stomoxys calcitrans? {^e^nm.)

3_ . — (Estrus. (Ibid.) Vol. I. p. 150.

4;. Semicomplete pupa. Cicada.

5. Subsemicoraplete ditto. Libellula. a. Mask. Vol. III.

p. 125—.

6. Incomplete ditto. Hydrophilus. (Lyonnet.) ^

Y. i - • Myme/eow emerging from its cocoon.

(Reaum.)

8. Vespa vulgaris.

9 . . Chironomus plumosus. (Reaum.)

a b. Respiratory plumes.
1 0, Obtected pupa, Apatura Iris.

11^ Vanessa Urticce. a. Head-case with

hvo points.

12. Gonepteryx Rhamni. a. Head-case with

one point.

» Vol. IV. p. 351. ii. III. Letter XXXIl. Vor., I. p. 65—.

EXPLANATION OF THE PLATES.

729

FIG.

13. Obtected pupa. Sphinx Ligustri. a. The tongue-case.
b. The eye-case. c. The trunk-case. d. First segment
of the abdomen, e. The adminicula. /. The mucro,
or point of the tail. Vol. III. p. '24-9— .

14), Hairy obtected pupa of Laria/ascelina.

PLATE XVII.'

1. Coarctate pupa. (Estrus hcemorrkoidalis. (Reaum.)

2. - Stratyomis chamcehon. (Ibid.) a. The

pupa as formed within the skin of the larva.

4. Oviform body which many pupae of Diptera at first as-

sume under the skin of the larva. (Ibid.) Vol. III.
p. 235.

8. The same when the parts begin to show themselves.
(Ibid.)

5. Cocoon of Satiirniapavonia. a. Pupa. 6. Threads that

close the orifice. Vol. III. p. 217, 279.

6. Loose and irregular ditto, of Arctia villica. Ibid. p. 220.

7. Boatshaped ditto, of Tortrix prasinana. Ibid. p. 221.

8. Network ditto, attached to the stalk of a plant.

9. Ditto, imitating the scales of fish. (Reaum.) Vol. I.

p. 462.

10. Spiral case of Trichopterous larva, formed of pieces of

leaf. (De Geer.)

11. Grate spun by these larvae to prevent ingress. (Ibid.)

Vol. II. p. 264.

12. Chilopodimorphous larva of Melolontha vulgaris. Vol.

III. p. 163.

13. Araneidiform? ditto o( Cicindela eampestris. Ibid. 1.52,

163.

PLATE XVIII. "

1. Anoplurimorphous larva. Chrysomela Populi. a. Osma-
ieria, or scent organs. Vol. II. p. 245. 111. p. 163, 166.

* Ubi supr.

VOL. ni.

" Vol. III. Letter XXXI.
3 B

730 EXPLANATION OF THE PLATES.

FIG.

2. Anopluriraorphous larva. Cassida. a. The fecifork co-

vered with excrement. Vol. IV. p. 353. 5.

3. Helminthiraorphous or vermiform ditto o( Balaninus JSlw

cum. Vol. III. p. 163.
4<. Chilognathimorphous ditto of Elaier Segetum. a. a. Spi-
racles.

5. Decapodimorphous ditto of Dytiscus marginalis. Vol. III.

p. 165.

6. Chilopodimorphous ditto of Staphylimcs? a. Anal pro-

leg.

7. Amphipodimorphous ditto of Acrida. Vol. III. p. 165.

8. Larva of Zelus.

9. Helminthiraorphous ditto. Apis mellifica. (Reaum.)

10. Larva of Sirex.

11. ■ ■ - Tenthredo L. (Reaum.) a. 6 legs. b. 16 pro-

legs.

12. ■ Sphinx, a. 6 legs. b. 10 prolegs. c. Anal horn.

13. Spinose ditto of Vanessa lo.

PLATE XIX,

1. Ijarya. of Papilio Machaon. ct. Its retractile osmaterium

emerging from its neck. Vol. II. p. 244—. III.
p. 148.

2. Larva of Cerura Vinula. a. Its anal mastigia. Vol. III.

p. 151.

3. Onisciform ditto of Thecla Rubi.

4. Larva of SitaMropMS Fa^. (Rdsel.) Vol. III. p. 133.

note

5. Notodonta ziczac. (Reaum.)

6. . Laria fascelina. a. Pencil of hairs, b. yer-

ricules of ditto, c. Fascicule of ditto. Vol. IV. p. 277.
3, 5, 7.

7. , of one of the Geometers in their attitude of

surveying.

Vol. III. Letter XXX F.

EXFLAXATIOS OF THE FLATE».

731

FIG.

8. AranaSSom hufa of Myrntdecm, (Beamn.)

9. Larva of C'tt/ea: /wpioi*. (Reaum.) fl. Tail. A. Befp*-

ratory appocattu.
10. _! or anroTumu* pbmosus. (Reamn.; a. Re*f*ira-

torj organs.

] J of a VoUicdla inhabiting the ne«t» of hmnWc-bee».

rKeaam,) /r. Anal tadii.
] 2. of EJ/zphUus pendulus. (Reaam.) a. Bapiratorjr

tuhKr-H.

]<? of Htraiyf/mi$ (^male/m. (Swamin.) a. Plumcf

of resspiratory orifice.

PLATE XX.*

1 . Lar%'a of a Mutca.

2. an (Ednu.

?j. Egg of Vanma Vrtkae. (Scpp.)

4, IlipjMirdd/i FUoidlce. (Ibid.)

5, . .. Hyjjeranlhuf. (Ibid.)

(■). . Geometra Cratcegala. (Ibid.)

7. Pierii Bratsica. (Ibid.)

^, . Ilipfxirchia JEgena. (Ibid.)

9. ()ura]Aeryz Sarnhncaria. (Ibid.)

10. • S'jfAm nupta. (Ibid.)

11. _ fraxzni, (Ibid.)

12. Geometra prunana. (Ibid.)

I'i . . armilUUa. (Ibid.)

14-. La-.i'/.amjja neuftria. (Reaum.)

1.5. H'.j'P'J- fJiia Jurlina. (Sepp.)

IG. Pcrdatvma. a. Bow-shaped spring, by which

the operculum is thrown o£ Vol. III. p. 104-

17. Ajn^ meUijka. (Reaam.)

18. Cidex jApienJt. (Ibid.) a. Summit.

\<), Scai</phaga. (Ibid.) a a. Auricles.

• UH supr. and Letter XXX.

7 32 EXPLANATION OF THE PLATES.

FIG.

20. Necklace of eggs. Vol. Ill, p. 67.

21. Egg of Tipula oleracea. (Reaurn.)

22. Ophion luteiim. (De Gear.) Vol. IV. p. 213 —

23. Nepa cinerea. (Swamm.)

24'. Jelly, with a necklace of eggs running in a spiral direc
tion fi-om end to end, taken out of the water.

25. Jelly of more consistence, enveloping the eggs Phry
gajiea atrata. Vol. III. p. 68.

Pnnted by Richard Taylor,
Shoe-Lane, London.

r/,./,- IS.

/•/.It. X.

F/ate jra.

TuueJan.

J'/a/.- .\7i:

Piate .--f/ 77.

J'/.l/r- XLl.

Internet Archive Audio

Featured

Top

Images

Featured

Top

Software

Featured

Top

Books

Featured

Top

Video

Featured

Top

Mobile Apps

Browser Extensions

Archive-It Subscription

Save Page Now

Full text of "An introduction to entomology, or, Elements of the natural history of insects : with plates [electronic resource]"

See other formats